Document system:sequences, all_sequences & vitals keyspaces

To https://docs.couchbase.com/server/current/n1ql/n1ql-intro/sysinfo.html add:

Querying Sequences

You can query sequences using the system:sequences keyspace as follows:

SELECT * FROM system:sequences;

The query returns the following attributes:

bucket (string) The bucket name.

cache (integer) The sequence's cache size.

cycle (boolean) If the sequence is defined to cycle or not.

increment (integer) The sequence step value.

min (integer) The minimum value permitted for the sequence.

max (integer) The maximum value permitted for the sequence.

name (string) The sequence's name.

namespace (string) Namespace to which the sequence belongs.

namespace_id (string) ID of the namespace to which the sequence belongs.

path (string) The fully qualified sequence name.

scope_id (string) The scope to which the sequence belongs.

value (object) The each field in the value is a node UUID reporting the integer sequence value on that node.  In addition the field "~next_block" reports the starting value of the next block of values that can be reserved for the sequence.

Note: Querying system:sequences only returns sequences that have been loaded (accessed since the last restart) on any node.  To see all defined sequences, use system:all_sequences.

To  https://docs.couchbase.com/server/current/manage/monitor/monitoring-n1ql-query.html#system-keyspaces add:

system:vitals

This keyspace reports the same information as the /admin/vitals REST endpoint.

Also add the table of contents link back to system:sequences in the "The following diagnostics are provided:" section on the page.

(Would be nice if a search on "system catalog(ue)" returned this list of system keyspaces as an initial result; I find it doesn't return a result for the list itself.)