docs(localization): fix outdated path in translate-help text

[dooly123]

What

The Please help us translate! panel in General Settings (rendered by SettingsProvider.BuildLanguageSelector in Basis/Packages/com.basis.framework/BasisUI/Menus/Main Menu Providers/SettingsProvider.cs) was telling contributors to look in StreamingAssets/Basis/Languages. That folder no longer exists — the language files moved into the framework package and are now loaded via Addressables.

Changes

• All 18 locale JSONs — replace the literal path StreamingAssets/Basis/Languages with Packages/com.basis.framework/BasisUI/Localization/Languages. The path was left untranslated in every locale, so swapping just the substring keeps each existing translation intact.
• en.json — additionally rewrite the description with clearer steps: rename the copy to your locale code (e.g. fr.json / ja.json) and open the PR at github.com/BasisVR/Basis.

What I did NOT change

• Localization keys are unchanged, so SettingsProvider.cs needs no edit.
• The title ("Please help us translate!" / equivalents) is unchanged in every language to avoid pointless retranslation churn.

Follow-ups for whoever merges

• The Languages addressable group probably needs a rebuild so the updated text ships in built players. Editor playmode picks it up directly from the package.
• The 17 non-English description strings are now slightly out of sync with English (they don't yet mention the locale-code rename or the GitHub URL). That's a translator-friendly nudge, not a blocker — the path is correct and the original instruction still works.