44962: vcs_info: Document internal function and variable

Functions/VCS_Info/VCS_INFO_bydir_detect

@@ -2,6 +2,18 @@
 ## Written by Frank Terbeck <ft@bewatermyfriend.org>
 ## Distributed under the same BSD-ish license as zsh itself.
 
+# Helper function for VCS_INFO_detect_*
+#
+# Usage:
+#     vcs_comm[detect_need_file]=FILENAMES VCS_INFO_bydir_detect DIRNAME
+# where DIRNAME is a directory name and FILENAMES is a space-separated list
+# of filenames.
+#
+# If any parent directory of the current working directory, other than the root
+# directory, contains a subdirectory named DIRNAME that contains a file whose name
+# is in FILENAMES, set vcs_comm[basedir] to the path of that parent directory and
+# return true.  Otherwise, return false.
+
 setopt localoptions NO_shwordsplit
 local dirname=$1
 local basedir="." file

Functions/VCS_Info/vcs_info

@@ -59,6 +59,12 @@ vcs_info () {
     local -x LC_MESSAGES
     local -i maxexports
     local -a msgs
+
+    # vcs_comm is used internally for passing values among VCS_INFO_* functions.
+    # It is not part of the public API.
+    #
+    # hook_com, backend_misc, and user_data are public API; see zshcontrib(1)
+    # and Misc/vcs_info-examples.
     local -A vcs_comm hook_com backend_misc user_data
 
     LC_MESSAGES=C