patch 8.2.1460: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more messages into errors.h.
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 87ae5f9..c08524f 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -5978,7 +5978,7 @@
     static void
 ex_wrongmodifier(exarg_T *eap)
 {
-    eap->errmsg = _(e_invcmd);
+    eap->errmsg = _(e_invalid_command);
 }
 
 /*