Revert "Enable in describe-function & describe-variable"

This reverts commit 60bfbe9b4284c084a20da67fdbf3abeb93a95849. Enabling
ido completion in these functions breaks a new feature, as described
here:
https://github.com/DarwinAwardWinner/ido-ubiquitous/issues/110#issuecomment-227926382

ido-ubiquitous.el

@@ -333,8 +333,6 @@ using overrides and disable it for everything else."
     (enable exact "find-tag")
     ;; https://github.com/DarwinAwardWinner/ido-ubiquitous/issues/89
     (enable prefix "etags-select-")
-    ;; https://github.com/DarwinAwardWinner/ido-ubiquitous/issues/110
-    (enable regexp "\\`describe-\\(function\\|variable\\)\\'")
     ) ; Close paren on separate line for better VC diffs
   "Default value of `ido-ubiquitous-command-overrides'.