Update translation setup

Since the only guide that uses the common directory is now the
cli-guide and we do not translate that one, disable translation of the
common directory as well.

Remove now obsolete setting of DIRECTORIES for zh_CN since those
were only relevant for the DocBook version of these.

Adopt comment for contributor-guide to move it under the do not
translate section, translation this content is not a focus right now.

Change-Id: I0ea32b15c7debba383c0840d1051a8812df2cdee

doc-tools-check-languages.conf

@@ -1,6 +1,5 @@
 # directories to be set up
 declare -A DIRECTORIES=(
-    ["zh_CN"]="common glossary"
 )
 
 # books to be built
@@ -34,10 +33,10 @@ declare -A SPECIAL_BOOKS=(
     ["networking-guide"]="RST"
     ["user-guide"]="RST"
     ["user-guide-admin"]="RST"
-    # Skip in-progress guides
-    ["contributor-guide"]="skip"
     # Do not translate
     ["cli-reference"]="skip"
+    ["common"]="skip"
+    ["contributor-guide"]="skip"
     # Skip arch design while its being revised
     ["arch-design-draft"]="skip"
     # This needs special handling, handle it with the RST tools.