Updated readme with:

* additional details for beginners,
* links to useful references,
* clarified how *.test.* files work now.

Author: Paul

README.md

@@ -1,56 +1,72 @@
 # Arduino CI Scripts
 
-This repos contains various scripts and tools related to running
-continuous integration (CI) checks on Arduino Library Repos.
+This repos contains various scripts and tools related to running continuous integration (CI) checks on Arduino Library Repos. The operations include:
+
+* checking formatting using using [clang-format](https://clang.llvm.org/docs/ClangFormat.html),
+* generating documentation from source comments using using [Doxygen](https://www.doxygen.nl/), and
+* building each example in the library for selected targets.
 
 There is an associated guide available here:
 https://learn.adafruit.com/the-well-automated-arduino-library/
 
 ## Adding GitHub Actions to Repo
 
+To run these continuous integration checks on each push, pull-request or [repository dispatch](https://docs.github.com/en/rest/repos/repos?apiVersion=2022-11-28#create-a-repository-dispatch-event) using [GitHub actions](https://github.com/features/actions):  
+
 * Create a folder named `.github/worflows` in the root of the repo.
 * Copy `example_actions.yml` into the above directory and rename it `githubci.yml`.
-* Edit `githubci.yml` and change `PRETTYNAME` to the library repo name.
+* Edit `githubci.yml` and change `PRETTYNAME` to the library repo name. Optionally, delete or comment out steps (using the `#` character), you don't want to include. 
 * Here's an example: [Adafruit_BME280_Library](https://github.com/adafruit/Adafruit_BME280_Library/blob/master/.github/workflows/githubci.yml)
-* These actions will now run automatically on any pull, push, or dispatch.
 
 ## Controlling Test Behavior
 
-The `build_platform.py` script is used to test each `.ino` example in the repo for the
-selected build platforms. The `ALL_PLATFORMS` dictionary contains a listing of all
-available platforms. By default, `main_platforms` is used. Additionally, UF2 files
-of the compiled sketches can be generated for supported platforms. The behavior
-can be controlled using special hidden filenames. These are just empty files
-placed in the root folder:
+The `build_platform.py` script is used to test each `.ino` example in the repo for selected build platforms. The [`ALL_PLATFORMS`](ci-arduino/blob/master/build_platform.py#L54) dictionary contains a listing of all available platforms and selected platform groups. By default, `main_platforms` is used. To select a specific platform or group, replace `main_platforms` in [`githubci.yml`](`example_actions.yml`) with the group or platform name.
+
+Additionally, [UF2 files](https://github.com/microsoft/uf2) of the compiled sketches can be generated for supported platforms. 
+
+### Fine tuning test selection
+
+The script behavior can be controlled using special filenames: 
 
 * `.YOUR_PLATFORM_HERE.test.skip` - Skip the specified platform. All others are tested.
-* `.YOUR_PLATFORM_HERE.test.only` - Test only the specfied platform. All others are skipped.
+* `.YOUR_PLATFORM_HERE.test.only` - Test the specified platform. All others are skipped.
 * `.YOUR_PLATFORM_HERE.generate` - Generate UF2 of sketch for specified platform (if supported).
 
-Replace `YOUR_PLATFORM_HERE` in the name with exact text from `ALL_PLATFORMS`.
-
-### Examples
+These are just empty files placed in an example folder. Replace `YOUR_PLATFORM_HERE` in the name with exact text from `ALL_PLATFORMS`. You can use several `.PLATFORM.test.skip` or `.PLATFORM.test.only` to exclude or include multiple platforms. For example:
 
 * To **skip** testing on ESP8266, add a file named `.esp8266.test.skip`
 * To test **only** the Arduino UNO, add a file named `.uno.test.only`
 * To skip all and test **nothing**, add a file named `.none.test.only`
 * To generate UF2s for PyPortal, add a file named `.pyportal.generate`
 
+### Dependencies
+
+Any library dependencies included in the [`library.properties`](https://arduino.github.io/arduino-cli/0.19/library-specification/#libraryproperties-file-format) are automatically installed before the tests are started. To install additional dependencies (e.g., those required for some examples but not the library itself) using [`arduino-cli`](https://arduino.github.io/arduino-cli/0.19/commands/arduino-cli_lib_install/), you could add additional steps to the `githubci.yml` file. For example:
+
+```yaml
+- name: Set configuration
+  run: arduino-cli config set library.enable_unsafe_install true 
+
+- name: Install test dependencies
+  run: arduino-cli lib install --git-url https://github.com/arduino-libraries/Servo --git-url https://github.com/arduino-libraries/Ethernet
+```
+
+Note: you'll only need to enable the [`enable_unsafe_install`](https://arduino.github.io/arduino-cli/0.32/configuration/#configuration-keys) option if you want to identify libraries using urls. This isn't necessary when using the library name. 
+
 ## Formatting Check with Clang
 
-The `run-clang-format.py` script is used to run ClangFormat and check file formatting.
+The `run-clang-format.py` script is used to run [clang-format](https://clang.llvm.org/docs/ClangFormat.html) and check file formatting.
 See [the guide](https://learn.adafruit.com/the-well-automated-arduino-library/formatting-with-clang-format) for details on installing `clang-format` to run formatting locally.
 Even a single extra white space can cause the CI to fail on formatting.
 You can typically just let clang do its thing and edit files in place using:
+
 ```
 clang-format -i File_To_Format.cpp
 ```
 
 ## Documentation with Doxygen
 
-The `doxy_gen_and_deploy.sh` script uses Doxygen to generate and deploy documentation
+The `doxy_gen_and_deploy.sh` script uses [Doxygen](https://www.doxygen.nl/) to generate and deploy documentation
 for the library. Any issues, like missing documentation, will cause the CI to fail.
-See the [the guide](https://learn.adafruit.com/the-well-automated-arduino-library/doxygen)
-for details on installing and running doxygen locally. The guide also has some
-[tips](https://learn.adafruit.com/the-well-automated-arduino-library/doxygen-tips)
-on basic usage of doxygen markup within your code.
+See the [the guide](https://learn.adafruit.com/the-well-automated-arduino-library/doxygen) for details on installing and running doxygen locally. The guide also has some
+[tips](https://learn.adafruit.com/the-well-automated-arduino-library/doxygen-tips) on basic usage of doxygen markup within your code.