Fix completion info call to use the correct ns

[PEZ]

What has Changed?

For the documentation part of the completion handler we were sending along whatever was in the "ns" entry in the item's insertText property. (In the case of symbols with aliased namespaces, this seems to have been the aliased namespace itself, how that could be I do not understand, but it is cool in a way.)

Now we send the document's namespace as any civilized nrepl client should be doing.

Fixes #1083

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