Help: target_include_directories does not allow target names

Since commit v2.8.11~227^2~1 (Don't allow targets args in the new target
commands, 2013-01-29) the target_include_directories command does not
support target names on the right hand side, but that commit forgot to
remove it from the docs.  It was never released with such support.
Update the command documentation now.

Help/command/target_include_directories.rst

@@ -9,8 +9,8 @@ Add include directories to a target.
     <INTERFACE|PUBLIC|PRIVATE> [items1...]
     [<INTERFACE|PUBLIC|PRIVATE> [items2...] ...])
 
-Specify include directories or targets to use when compiling a given
-target.  The named ``<target>`` must have been created by a command such
+Specify include directories to use when compiling a given target.
+The named ``<target>`` must have been created by a command such
 as :command:`add_executable` or :command:`add_library` and must not be an
 :prop_tgt:`IMPORTED` target.