in API schema for metadata endpoint, change versionindex to bibleindex

[JohnRDOrazio]

The query parameter of the metadata endpoint can take one of three values:

• bibleversions
• biblebooks
• versionindex

The reason for the third possible value having a different naming scheme compared to the first two was because this parameter required a second parameter version. This does make sense, and perhaps we could leave it like this. On the other hand it might be more intuitive if it did follow the naming scheme of the first two, it might seem more coherent and harmonious. This would mean changing it from versionindex to say bibleindex.

Just a thought, not sure if we should follow up on this or not.