patch 8.2.3983: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 88a2c04..bea2846 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -4540,7 +4540,7 @@
 {
     if (!eap->skip)
 	eap->errmsg =
-		_("E319: Sorry, the command is not available in this version");
+		_(e_sorry_command_is_not_available_in_this_version);
 }
 
 #ifdef HAVE_EX_SCRIPT_NI