[Wdocumentation] improve wording of a warning message

Based on @davezarzycki remarks in D64696 improved the wording of the warning
message.

Differential Revision: https://reviews.llvm.org/D66700

Patch by Mark de Wever.

llvm-svn: 369873

clang/include/clang/Basic/DiagnosticCommentKinds.td

@@ -156,7 +156,7 @@ def note_add_deprecation_attr : Note<
 // inline contents commands
 
 def warn_doc_inline_contents_no_argument : Warning<
-  "'%select{\\|@}0%1' command does not have an argument">,
+  "'%select{\\|@}0%1' command does not have a valid word argument">,
   InGroup<Documentation>, DefaultIgnore;
 
 // verbatim block commands

clang/test/Sema/warn-documentation.cpp

@@ -1050,42 +1050,42 @@ template <typename B>
 void test_attach38<int>::test_attach39(int, B);
 
 // The inline comments expect a string after the command.
-// expected-warning@+1 {{'\a' command does not have an argument}}
+// expected-warning@+1 {{'\a' command does not have a valid word argument}}
 /// \a
 int test_inline_no_argument_a_bad(int);
 
 /// \a A
 int test_inline_no_argument_a_good(int);
 
-// expected-warning@+1 {{'@b' command does not have an argument}}
+// expected-warning@+1 {{'@b' command does not have a valid word argument}}
 /// @b
 int test_inline_no_argument_b_bad(int);
 
 /// @b A
 int test_inline_no_argument_b_good(int);
 
-// expected-warning@+1 {{'\c' command does not have an argument}}
+// expected-warning@+1 {{'\c' command does not have a valid word argument}}
 /// \c
 int test_inline_no_argument_c_bad(int);
 
 /// \c A
 int test_inline_no_argument_c_good(int);
 
-// expected-warning@+1 {{'\e' command does not have an argument}}
+// expected-warning@+1 {{'\e' command does not have a valid word argument}}
 /// \e
 int test_inline_no_argument_e_bad(int);
 
 /// \e A
 int test_inline_no_argument_e_good(int);
 
-// expected-warning@+1 {{'\em' command does not have an argument}}
+// expected-warning@+1 {{'\em' command does not have a valid word argument}}
 /// \em
 int test_inline_no_argument_em_bad(int);
 
 /// \em A
 int test_inline_no_argument_em_good(int);
 
-// expected-warning@+1 {{'\p' command does not have an argument}}
+// expected-warning@+1 {{'\p' command does not have a valid word argument}}
 /// \p
 int test_inline_no_argument_p_bad(int);