Merge pull request #659 from gareth-nx/readme_update

Readme update

Author: jvdp1

README.md

@@ -133,12 +133,14 @@ Important options are
   Compiling with maximum rank 15 can be resource intensive and requires at least 16 GB of memory to allow parallel compilation or 4 GB memory for sequential compilation.
 - `-DBUILD_SHARED_LIBS` set to `on` in case you want link your application dynamically against the standard library (default: `off`).
 - `-DBUILD_TESTING` set to `off` in case you want to disable the stdlib tests (default: `on`).
+- `-DCMAKE_VERBOSE_MAKEFILE` is by default set to `Off`, but if set to `On` will show commands used to compile the code.
+- `-DCMAKE_BUILD_TYPE` is by default set to `RelWithDebInfo`, which uses compiler flags suitable for code development (but with only `-O2` optimization). Beware the compiler flags set this way will override any compiler flags specified via `FFLAGS`. To prevent this, use `-DCMAKE_BUILD_TYPE=NoConfig` in conjunction with `FFLAGS`.
 
-For example, to configure a build using the Ninja backend while specifying compiler flags `FFLAGS`, generating procedures up to rank 7, and installing to your home directory, use
+For example, to configure a build using the Ninja backend while specifying compiler optimization via `FFLAGS`, generating procedures up to rank 7, installing to your home directory, using the `NoConfig` compiler flags, and printing the compiler commands, use
 
 ```sh
 export FFLAGS="-O3"
-cmake -B build -G Ninja -DCMAKE_MAXIMUM_RANK:String=7 -DCMAKE_INSTALL_PREFIX=$HOME/.local
+cmake -B build -G Ninja -DCMAKE_MAXIMUM_RANK:String=7 -DCMAKE_INSTALL_PREFIX=$HOME/.local -DCMAKE_VERBOSE_MAKEFILE=On -DCMAKE_BUILD_TYPE=NoConfig
 ```
 
 To build the standard library run