DOC-7529: System keyspaces

[simon-dew]

The following draft documentation is ready for review:

• Getting System Information

Docs issue: DOC-7529

[marcogrecopriolo]

All perfect. Just one little note (and it's probably my bad...)
Aside from system:scopes, system:keyspaces, system:indexes, we also have system:all_scopes, system:all_keyspaces, system:all_indexes.
They look exactly the same as the non 'all_' counterpart, but also list system objects, so for instance system:all_scopes would list '_default' scopes, which system:scopes, wouldn't, system:all_keyspaces would list all the system keyspaces and would list the same keyspace twice, once as default:bucket1 and once as default:bucket1._default._default, and system:all_indexes would also list indexes on system:keyspaces.

If you think these are confusing, we can just leave them undocumented.

[simon-dew]

Thanks @marcogrecopriolo. I've actually documented system:all_scopes as a note under the Querying Scopes heading, system:all_keyspaces as a note under the Querying Collections heading, and system:all_indexes as a note under the Querying Indexes heading. I wanted to make sure they were documented, but didn't want to get bogged down in details because as you say the behavior of system:all_keyspaces is confusing.

[marcogrecopriolo]

perfect!

[simon-dew]

Update links to staging docs