[8.x] [DOCS] Add examples for mget, msearch template APIs (#3615)

[lcawl]

Backport

This will backport the following commits from main to 8.x:

• [DOCS] Add examples for mget, msearch template APIs (#3615)

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
field_caps	🟢	63/63	63/63
knn_search	🟢	4/4	4/4
mget	🟢	51/51	50/50
msearch_template	🟢	1/1	1/1
mtermvectors	🟢	10/10	10/10
rank_eval	⚪	Missing test	Missing test
scroll	🟢	69/69	20/20
search_mvt	⚪	34/34	Missing test
search	🔴	2275/2352	2333/2334
terms_enum	🟢	47/47	47/47

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