[8.17] [DOCS] Add examples for create, delete, index, reindex APIs (#3540)

[lcawl]

Backport

This will backport the following commits from main to 8.17:

• [DOCS] Add examples for create, delete, index, reindex APIs (#3540)

Questions ?

Please refer to the Backport tool documentation

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
cluster.put_settings	🟢	59/59	58/58
create	🟢	24/24	23/23
delete	🟢	37/37	37/37
exists_source	🟢	3/3	3/3
exists	🟢	19/19	19/19
get_source	🟢	18/18	18/18
get	🟢	299/299	296/296
index	🟢	1144/1144	1146/1146
reindex_rethrottle	🟢	2/2	2/2
reindex	🟢	15/15	14/14
update	🟢	35/35	35/35

You can validate these APIs yourself by using the make validate target.