Update CODEOWNERS

[bmorelli25]

Unfortunately, I think the easiest solution for the get-started dir is to add both ingest and exp docs. That's noisy, but it's a small number of files so hopefully it's okay. The other two options would be to either:

1. Separate the files into different dirs based on ownership (maybe this is preferable?)
2. Add file-specific rules for each file in the dir (this feels too difficult to maintain)