Add 'mtree' output format to completion.yaml with monochrome description

Author: nmaguiar

data/completion.yaml

@@ -263,6 +263,8 @@ complete:
     desc: A table-like forcely colored format -only for list outputs-
   - name: out=ctree
     desc: A tree-like forcely colored format
+  - name: out=mtree
+    desc: A tree-like forcely monochrome format
   - name: out=cyaml
     desc: An YAML colored format
   - name: out=db
@@ -632,4 +634,4 @@ complete:
 - name: xrfn=
   desc: A javascript code, receiving each input array record as 'args' and return it's code evaluation
 - name: val2icon= 
-  desc: If defined will transform undefined, null and boolean values to emoticons -values can be 'default' or 'simple'-
+  desc: If defined will transform undefined, null and boolean values to emoticons -values can be 'default' or 'simple'-