[Ada] String literal is allowed for pragma Warnings in Ada 83

[Arnaud Charlet]

Documentation change only, no further test required

Tested on x86_64-pc-linux-gnu, committed on trunk

2014-10-17  Robert Dewar  <de...@adacore.com>

        * gnat_rm.texi: Document that string literal can be used for
        pragma Warnings when operating in Ada 83 mode.


Index: gnat_rm.texi
===================================================================
--- gnat_rm.texi        (revision 216371)
+++ gnat_rm.texi        (working copy)
@@ -7829,6 +7829,9 @@
 pragma Warnings (On | Off, static_string_EXPRESSION [,REASON]);
 
 REASON ::= Reason => STRING_LITERAL @{& STRING_LITERAL@}
+
+Note: in Ada 83 mode, a string literal may be used in place of
+a static string expression (which does not exist in Ada 83).
 @end smallexample
 
 @noindent