Update codebase to be WP Coding Standard-compliant.

This is a squashed copy of `wp-coding-standard--rebase` to try and fix the line-ending
diff issue we're having.

README.md

@@ -14,6 +14,7 @@ Featured on [wpmudev](http://premium.wpmudev.org/blog/12-surprisingly-useful-wor
 
 1. Read the contributing guidelines
 1. Clone this repository (`git clone git@github.com:markcheret/footnotes.git`)
+  - We recommend that you use [VVV](https://varyingvagrantvagrants.org/) for your development environment
 1. Install [Composer](https://getcomposer.org/download/), if you don't have it already
 1. Install dependencies (`composer install`)
 1. Create a new branch from `main` (`git checkout -b <your-descriptive-branch-name>`)
@@ -25,8 +26,8 @@ Featured on [wpmudev](http://premium.wpmudev.org/blog/12-surprisingly-useful-wor
 1. Run PHP_CodeSniffer on the file(s) you want to check (`./vendor/bin/phpcs --standard="WordPress" --colors --encoding=utf-8 -n -p <file(s)>`)
 1. (If applicable) run the PHP Code Beautifier and Formatter to attempt to automatically fix any errors (`./vendor/bin/phpcbf --standard="WordPress" --encoding=utf-8 -p <file(s)>`)
   - Add the `-n` flag to ignore warnings (i.e., show only errors)
-	- Add the `-s` flag to show sniff codes (used for disabling errors in the code with `phpcs disable:<sniff code>` — MAKE SURE THAT YOU HAVE `phpcs enable` AT THE EARLIEST POINT POSSIBLE, and provide a justification for disabling the sniff code)
-  - You can run either across the entire project by adding the argument `--ignore=*/vendor/*` and targetting the file `./*.php ./**/*.php`
+  - Add the `-s` flag to show sniff codes (used for disabling errors in the code with `phpcs disable:<sniff code>` — MAKE SURE THAT YOU HAVE `phpcs enable` AT THE EARLIEST POINT POSSIBLE, and provide a justification for disabling the sniff code)
+  - You can run either across the entire project by adding the argument `--ignore=*/vendor/*` and targetting the file `./**/*.php`
 
 ## Updating Documentation