[PATCH] Document that most directives are case insensitive

[Ciro Santilli]

I saw a `.SECTION` directive written in uppercase, and I was in doubt
if it should work.

After reading `read.c`, I think this is the case, because of the
TOLOWER inside `#ifned TC_CASE_SENSITIVE`. `TC_CASE_SENSITIVE` is only
set for metag.

---
 gas/doc/as.texinfo | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gas/doc/as.texinfo b/gas/doc/as.texinfo
index 6694b23..7770912 100644
--- a/gas/doc/as.texinfo
+++ b/gas/doc/as.texinfo
@@ -4205,7 +4205,8 @@ address; you can only have a defined section in
one of the two arguments.
 @cindex pseudo-ops, machine independent
 @cindex machine independent directives
 All assembler directives have names that begin with a period (@samp{.}).
-The rest of the name is letters, usually in lower case.
+The rest of the name is made of letters. The names are case insensitive
+for most architectures, and usually written in lower case.

 This chapter discusses directives that are available regardless of the
 target machine configuration for the @sc{gnu} assembler.
-- 
1.9.1