Docs: Update PHP_CodeSniffer repository link - #39

Changed pages include:

• index.html - view
• 404.html - view
• introduction/index.html - view
• javascript/index.html - view
• php/index.html - view
• react/index.html - view
• web-component/index.html - view
• wordpress/index.html - view
• javascript/_codesandbox/index.html - view
• javascript/_github-repo/index.html - view

There are more changes not included in the list