add completion for nvm

completion/available/nvm.completion.bash

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+# nvm (Node Version Manager) completion
+
+if [ -r $NVM_DIR/bash_completion ]
+then
+  . $NVM_DIR/bash_completion
+else
+  echo "Enable nvm plugin first"
+fi