The Rename mode enhancement is available under the Options button (top right of the documents list). Check this option to enter rename mode, and uncheck the option to exit rename mode.
While rename mode is active, clicking the document names will no longer open the document, but rather changes the name to an entry field. This capability is particularly useful to quickly update the names after batch uploading documents to the system.
Note: when this mode is turned on a dotted line appears below each document that can be renamed. Simply click once on the name to make a change.