Fixed versionchanged indentation in docs/.

My thinking in cases like this has been that if everything to the end of the section describes changes, then the indentation does not really offer any additional clarity. Also, when we go to remove the "versionchanged" annotation (we keep them around for 2 releases), then we won't have to deindent the same text and create more changes. It might be better simply put the text like "If a file with ``name`` already exists,..." above the versionchanged block and only "Previously, ..." inside the block (indented) -- then the entire versionchanged block and its contents could be deleted when the time comes and we wouldn't need to change any indent levels.