Refine ECMASCRIPT.md

[smorimoto]

• Fix the document filename
• Link compatible tables directly
  • MDN for browsers and Node.js
  • Node.js official documentation for Node.js

[Copilot]

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (4)

EMCASCRIPT.md:8

• [nitpick] The term 'rest parameters' should be consistently capitalized as 'Rest Parameters' to match the other section titles.

### rest parameters

EMCASCRIPT.md:11

• [nitpick] The term 'spread in function call' should be consistently capitalized as 'Spread Syntax (in function call)' to match the other section titles.

### spread in function call

EMCASCRIPT.md:17

• [nitpick] The term 'ArrowFunction' should be consistently written as 'Arrow Function Expressions' to match the other section titles.

### ArrowFunction

EMCASCRIPT.md:27

• The term 'polyfill-ed' should be corrected to 'Polyfilled' for clarity and consistency.

-- polyfill-ed in the repo

[hhugo]

• Fix the document filename

This is now on master. You can rebase and we'll hopefully get better diff for this PR

[smorimoto]

Done