Improve support for Cham script

* lisp/language/cham.el ("Cham"): Expand the entry.

* etc/HELLO: Add entry for Cham.

etc/HELLO

@@ -30,6 +30,8 @@ Bengali (বাংলা)	নমস্কার
 Braille	⠓⠑⠇⠇⠕
 Burmese (မြန်မာ)	မင်္ဂလာပါ
 C	printf ("Hello, world!\n");
+Cham (ꨌꩌ)	ꨦꨤꩌ ꨦꨰꨁ
+
 Cherokee (ᏣᎳᎩ ᎦᏬᏂᎯᏍᏗ)	ᎣᏏᏲ / ᏏᏲ
 Comanche /kəˈmæntʃiː/	Haa marʉ́awe
 

lisp/language/cham.el

@@ -34,6 +34,11 @@
 (set-language-info-alist
  "Cham" '((charset unicode)
 	      (coding-system utf-8)
-	      (coding-priority utf-8)))
+	      (coding-priority utf-8)
+              (sample-text . "Cham (ꨌꩌ)\tꨦꨤꩌ ꨦꨰꨁ")
+              (documentation . "\
+The Cham script is a Brahmic script used to write Cham,
+an Austronesian language spoken by some 245,000 Chams
+in Vietnam and Cambodia.")))
 
 (provide 'cham)