change UI element names on document tab to better reflect shown content

It appears that the documents shown for a given user do not reflect the headings offered by the documents tab. As best as I can tell:

My Documents: shows ALL shared documents as well as the current user's private docs

All Documents: shows all shared documents, including the current user's shared documents.

While this could be a bugfix, the path of least resistance would just be to change the element names to better reflect what is visible to the user. I'm submitting a pull request which does just this.