Added function to mkdir and immediately change to it

lib/directories.zsh

@@ -36,5 +36,9 @@ cd () {
 
 alias md='mkdir -p'
 alias rd=rmdir
-
 alias d='dirs -v'
+
+# mkdir & cd to it
+function mcd() { 
+  mkdir -p "$1" && cd "$1"; 
+}