REST API: more ambiguous strings ("The object...")

[jnylen0]

[39342] clarified a lot of strings like "The caption for the resource." using more specific object types. However, there are still alot left that use "object" instead of "resource":

​https://gist.github.com/nylen/359d02d837c64911760a8b95217e53d1

We should also update these to use more specific object types.

cc @ramiy in case you are interested in working on this for 4.8 - but to make it in, it needs a patch in the next day or so.

[ocean90]

Removed i18n-change because it's only required during string freezes.

[ramiy]

@jnylen0 thanks for the CC, I will do my part like I do before every major release. But my audit depends on ​translate.wordpress.org. When 4.8 strings will be imported to glotpress I will commit my patches.