Initial cspell and prettier support

[davidjharder]

Changes

• Add cspell and prettier to the project as yarn dependencies
• Create a config and custom word-list for cspell
• Update README
• Add Actions for cspell and prettier

Actions description

• spellcheck
  • cspell is used to check spelling against standard dictionaries and a custom word list.
  • Warnings are generated for bad spellings, but the check will still pass
• prettier
  • Format changed markdown pages and write the changes as a new commit on the PR

See these checks in action here:

• https://github.com/davidjharder/help-center-docs/pull/10
• https://github.com/davidjharder/help-center-docs/pull/9

[davidjharder]

YOLO