Add CI workflow to check for commonly misspelled words

On every push, pull request, and periodically, use the codespell-project/actions-codespell action to check for commonly
misspelled words.

In the event of a false positive, the problematic word should be added, in all lowercase, to the ignore-words-list field
of ./.codespellrc. Regardless of the case of the word in the false positive, it must be in all lowercase in the ignore
list. The ignore list is comma-separated with no spaces.

Author: per1234

.codespellrc

@@ -0,0 +1,7 @@
+# See: https://github.com/codespell-project/codespell#using-a-config-file
+[codespell]
+# In the event of a false positive, add the problematic word, in all lowercase, to a comma-separated list here:
+ignore-words-list = ,
+check-filenames =
+check-hidden =
+skip = ./.git

.github/workflows/spell-check.yml

@@ -0,0 +1,22 @@
+name: Spell Check
+
+# See: https://docs.github.com/en/free-pro-team@latest/actions/reference/events-that-trigger-workflows
+on:
+  push:
+  pull_request:
+  schedule:
+    # Run every Tuesday at 8 AM UTC to catch new misspelling detections resulting from dictionary updates.
+    - cron: "0 8 * * TUE"
+  workflow_dispatch:
+  repository_dispatch:
+
+jobs:
+  spellcheck:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Spell check
+        uses: codespell-project/actions-codespell@master

README.adoc

@@ -1,11 +1,16 @@
-= MIDIUSB Library for Arduino =
+:repository-owner: arduino-libraries
+:repository-name: MIDIUSB
+
+= {repository-name} Library for Arduino =
+
+image:https://github.com/{repository-owner}/{repository-name}/actions/workflows/spell-check.yml/badge.svg["Spell Check status", link="https://github.com/{repository-owner}/{repository-name}/actions/workflows/spell-check.yml"]
 
 This library allows an Arduino board with USB capabilites to act as a MIDI instrument over USB. The library is based on PluggableUSB, so is only compatible with IDE 1.6.6 and nightly builds (AVR core > 1.6.8, SAM core > 1.6.4, SAMD core > 1.6.1)
 
 Furthermore, since PluggableUSB only targets boards with native USB capabilities, this library only supports these boards (eg. Leonardo, Micro, Due, Zero and so on)
 
 For more information about this library please visit us at
-http://www.arduino.cc/en/Reference/MIDIUSB
+http://www.arduino.cc/en/Reference/{repository-name}
 
 == Test procedure (Linux) ==