docs(oauth): fix broken 127.0.0.1 workaround URL and invalid JSON in token examples

[loco306]

What

Three small correctness fixes in getting-started/generating-tokens-oauth2-flow.md:

1. 127.0.0.1 workaround example - added the missing & after the sacrificial redirect=127.0.0.1 parameter. As written, redirect=127.0.0.1 runs straight into redirect_uri=..., so the query string parses as a single redirect parameter and redirect_uri is dropped entirely - copying the documented workaround produces a request with no redirect_uri, and authorization fails.
   2 & 3. App Access Token examples - removed trailing commas before the closing brace in two JSON snippets (the 200 response tab and the Example Response) so they are valid JSON.

Verification

• Parsing the corrected authorize URL now yields redirect_uri=http://127.0.0.1/callback as its own parameter (previously absent).
• Both App Access Token JSON examples now parse as valid JSON.

Net change: one & added, two commas removed.