Update for POST /{db}/_index

[b0wter]

Overview

I am opening this pr in reference to #598
I've updated the following:

1. added a missing status code (404)
2. removed partial_filter_selector from the query parameters (since it should be a property of the index parameter)
3. updated the index query parameter (it is no longer a list of strings but a json object)
4. changed the example that showcases the use of all query parameters

Testing recommendations

Use any tool to send a http request to couchdb using the example given in the pr. I've tested it with Couch DB 3.1.1 and get the following response:

result": "exists",
    "id": "_design/example-ddoc",
    "name": "example-index"
}

(I've run multiple tests that's why the index already exists)

Checklist

• Update rebar.config.script with the commit hash once this PR is rebased and merged

[wohali]

Minor formatting changes - overall this looks good.

[wohali]

This section should be formatted similar to this:

https://github.com/apache/couchdb-documentation/blame/main/src/api/server/common.rst#L644-L658

Use the same :json ... type structure so that all of the fields render correctly.

[b0wter]

I've updated the PR. Here is a screenshot of what the new part looks like:

Let me know if this is not the way it's supposed to be :)

[wohali]

Thanks @b0wter !