Add Github workflows for compiling examples and spell checking

Author: sandeepmistry

.github/workflows/compile-examples.yml

@@ -0,0 +1,21 @@
+name: Compile Examples
+on: [push, pull_request]
+jobs:
+ build:
+   runs-on: ubuntu-latest
+
+   strategy:
+     matrix:
+       fqbn: [
+         "arduino:avr:uno",
+         "arduino:samd:mkrzero"
+       ]
+
+   steps:
+     - uses: actions/checkout@v1
+       with:
+         fetch-depth: 1
+     - uses: arduino/actions/libraries/compile-examples@master
+       with:
+         fqbn: ${{ matrix.fqbn }}
+         libraries: ArduinoRS485

.github/workflows/spell-check.yml

@@ -0,0 +1,11 @@
+name: Spell Check
+on: [push, pull_request]
+jobs:
+ build:
+   runs-on: ubuntu-latest
+
+   steps:
+     - uses: actions/checkout@v1
+       with:
+         fetch-depth: 1
+     - uses: arduino/actions/libraries/spell-check@master

README.adoc

@@ -1,5 +1,7 @@
 = DMX Library for Arduino =
 
+image:https://github.com/arduino-libraries/ArduinoDMX/workflows/Compile%20Examples/badge.svg["Compile Examples Status", link="https://github.com/arduino-libraries/ArduinoDMX/actions?workflow=Compile+Examples"] image:https://github.com/arduino-libraries/ArduinoDMX/workflows/Spell%20Check/badge.svg["Spell Check Status", link="https://github.com/arduino-libraries/ArduinoDMX/actions?workflow=Spell+Check"]
+
 Control DMX lights with your Arduino. 
 
 Using RS485 shields, like the MKR 485 Shield. This library depends on the ArduinoRS485 library.