Generalize references to APIs

[shainaraskas]

To avoid confusing people reading these docs in the client references, I'm removing explicit references to endpoints and endpoint names, and going back to general API names. We might revisit this as we improve our link tech.

[github-actions]

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

API	Status	Request	Response
cat.aliases	🟢	30/30	30/30
cat.component_templates	⚪	Missing test	Missing test
cat.count	🟢	9/9	9/9
cat.indices	🔴	35/35	24/34
cat.ml_data_frame_analytics	🟢	5/5	5/5
cat.ml_datafeeds	🟢	4/4	4/4
cat.ml_jobs	🟢	4/4	4/4
cat.ml_trained_models	🟢	1/1	1/1
cat.transforms	🟢	7/7	7/7

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

[lcawl]

LGTM!