Adds index API requests and responses - part 2

[szabosteve]

Overview

Related to #2482.
This PR adds request and response examples to the index API. As this is an extensive namespace, I separated the work into two PRs, so it's easier to overview/review. This is the second PR.

First PR: #2979

[github-actions]

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

API	Status	Request	Response
indices.put_index_template	🔴	52/62	62/62
indices.put_mapping	🔴	111/115	115/115
indices.put_settings	🔴	54/57	57/57
indices.put_template	🔴	45/46	46/46
indices.recovery	🟢	9/9	9/9
indices.resolve_cluster	🔴	10/12	12/12
indices.resolve_index	🟢	6/6	6/6
indices.rollover	🔴	26/26	1/26
indices.shrink	🟢	5/5	5/5
indices.split	🟢	11/11	11/11

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

[github-actions]

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

API	Status	Request	Response
indices.put_index_template	🔴	52/62	62/62
indices.put_mapping	🔴	111/115	115/115
indices.put_settings	🔴	54/57	57/57
indices.put_template	🔴	45/46	46/46
indices.recovery	🟢	9/9	9/9
indices.resolve_cluster	🔴	10/12	12/12
indices.resolve_index	🟢	6/6	6/6
indices.rollover	🔴	26/26	1/26
indices.shrink	🟢	5/5	5/5
indices.split	🟢	11/11	11/11

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