Fix 'Release Notes' link on versions page

[jakewtaylor]

This fixes a problem with the 'Release Notes' link on the versions page.

There was an unwrapped ternary expression:

<a
  href={
    "https://github.com/facebook/react-native/releases/tag/v" +
    version +
    ".0" +
    isRc
      ? "-rc.0"
      : ""
  }
>
  Release Notes
</a>

Which evaluates like:

("https://github.com/facebook/react-native/releases/tag/v" + version + ".0" + isRc) ? "-rc.0" : ""

Making the href attribute always -rc.0.

The fix just wraps the ternary statement in brackets, for the intended functionality:

<a
  href={
    "https://github.com/facebook/react-native/releases/tag/v" +
    version +
    ".0" +
    (isRC ? "-rc.0" : "")
  }
>
  Release Notes
</a>

Which, obviously, evaluates like:

"https://github.com/facebook/react-native/releases/tag/v" + version + ".0" + (isRc ? "-rc.0" : "")

I also fixed unique 'key' prop warnings in the same file, by moving the key to the VersionItem component itself rather than the tr element inside the VersionItem component.

Also some Prettier fixes that were nothing to do with me, but couldn't commit without them. 😛