37664: docs: Document the completion function _command_names.

ChangeLog

@@ -1,3 +1,8 @@
+2016-01-20  Daniel Shahaf  <d.s@daniel.shahaf.name>
+
+	* 37664: Completion/Unix/Type/_path_commands, Doc/Zsh/compsys.yo:
+	docs: Document the completion function _command_names.
+
 2016-01-19  Peter Stephenson  <p.stephenson@samsung.com>
 
 	* 37693: Src/glob.c: turn Dash into '-' in glob qualifiers.

Completion/Unix/Type/_path_commands

@@ -82,6 +82,9 @@ if [[ -n $need_desc ]]; then
 else
   _wanted commands expl 'external command' compadd "$@" -k commands && ret=0
 fi
+# TODO: this is called from '_command_names -e' which is typically used in
+# contexts (such as _env) that don't accept directory names.  Should this
+# 'if' block move up to the "_command_names -" branch of _command_names?
 if [[ -o path_dirs ]]; then
   local -a path_dirs
   path_dirs=(${^path}/*(/N:t))

Doc/Zsh/compsys.yo

@@ -4203,6 +4203,12 @@ All arguments after the required field name are passed to
 tt(compadd) when generating matches from the style value, or to 
 the functions for the fields if they are called.
 )
+findex(_command_names)
+item(tt(_command_names) [ tt(-e) | tt(-) ])(
+This function completes words that are valid at command position: names of
+aliases, builtins, hashed commands, functions, and so on.  With the tt(-e)
+flag, only hashed commands are completed.  The tt(-) flag is ignored.
+)
 findex(_describe)
 redef(SPACES)(0)(tt(ifztexi(NOTRANS(@ @ @ @ @ @ @ @ @ @ ))ifnztexi(          )))
 xitem(tt(_describe )[tt(-12JVx)] [ tt(-oO) | tt(-t) var(tag) ] var(descr) var(name1) [ var(name2) ] [ var(opt) ... ])