Add key-specs notes (#10193)

Add optional `notes` to keyspecs.

Other changes:

1. Remove the "incomplete" flag from SORT and SORT_RO: it is misleading since "incomplete" means "this spec may not return all the keys it describes" but SORT and SORT_RO's specs (except the input key) do not return any keys at all.
So basically:
If a spec's begin_search is "unknown" you should not use it at all, you must use COMMAND KEYS;
if a spec itself is "incomplete", you can use it to get a partial list of keys, but if you want all of them you must use COMMAND GETKEYS;
otherwise, the spec will return all the keys

2. `getKeysUsingKeySpecs` handles incomplete specs internally

0 files changed, 0 insertions, 0 deletions