docs: fix minor typos, grammar, and formatting

[NssGourav]

Overview

This pull request addresses several small but meaningful issues across the documentation files to improve overall clarity, fix minor spelling/grammar mistakes, and correct formatting inconsistencies.

Changes Made:

• README.md: Fixed "Javascript" to "JavaScript", replaced code backticks with clearer complete sentences (e.g., changing "by script" to "by the script tag"), added missing commas, and fixed phrasing flow.
• CONTRIBUTING.md: Corrected "diverse background" to "diverse backgrounds", updated the deprecated nvm repository link (creationix -> nvm-sh), capitalized "For M1 Mac users" properly, and fixed missing punctuation.
• BUILDING.md: Fixed a typo ("it's" -> "its"), corrected missing closing quotes in the Webpack configuration string, and improved readability.
• CUSTOM_BUNDLE.md: Refined phrasing for better clarity (e.g., changing "then could switch..." to "then you can switch...") and added required commas.
• SECURITY.md: Added missing commas following transition phrases like "For example".

All changes are strictly non-breaking and isolated to the documentation/markdown files, ensuring a safe and simple review process.

[camdecoster]

Thanks for cleaning things up! I'm going to approve this and push a commit to fix the schema test. You didn't break it, but this is a convenient PR to take care of it.