Need to provide more detail on what the query request memory quota represent

Query service provides a request memory-quota setting, which customer has found that the query service can still exceed the value when processing a query. This is because, the setting only takes into account the memory used by the documents in the query service. Transient memory that is used by the query serve code, such as heap and stack are not accounted for, thus causing the Query service actual memory usage for a query to exceed the value set by the request memory quota.   CBSE-14580

We need to add this information to the doc page where we document request memory quota.

https://docs.couchbase.com/server/current/settings/query-settings.html#queryMemoryQuota

Specifically, under the queryMemoryQuota, memory-quota, and memory_quota

Original description :

Within a transaction, this parameter enforces the memory quota for the transaction. The transaction memory quota tracks only the delta table and the transaction log (approximately).

New description :

This parameter enforces a ceiling on the memory used for tracked documents required for processing a request. It does not take into account any other memory used to process the request, such as the stack, the operators, some intermediate values, etc.  Within a transaction, this parameter in addition enforces the memory quota for the transaction by tracking the delta table and the transaction log (approximately).