DebugMeta needs update with Portable PDB changes

[vaind]

There were some changes to the protocol in order to support Portable PDBs but they're not yet reflected in the development docs.

• https://develop.sentry.dev/sdk/event-payloads/debugmeta needs update
• based on https://github.com/getsentry/rfcs/blob/main/text/0013-portable-pdb.md#implementation

Another issue but on the same page: type says Must be "macho". but that doesn't seem right.

[marandaneto]

@vaind this one should be up to date because its automatically deployed https://develop.sentry.dev/sdk/event-payloads/types/#typedef-DebugMeta