zk: Add new inbox note function

Add simple alias function which allows quickly creating a note destined
for the inbox by typing `nni`.

writing/zk/config/sh/alias.d/zk.sh

@@ -26,6 +26,9 @@ if [ -n "${WIKIROOT}" ]; then
     nn() { # 'new note'
         _zk_wiki new "$@"
     }
+    nni() { # 'new note inbox'
+        _zk_wiki new -t "${*}" inbox
+    }
     nnl() { # 'new note log'
         _zk_wiki log "$@"
     }