state that LCC is a C89 compiler

The README does not currently state that LCC is a C89 compiler. While this can be inferred based on the book's publication date of 1995, it causes much confusion (see drh#47). This patch adds a blurb to the README informing users that it is a C89 compiler; a warning to not run C99 should hopefully not be necessary.

Signed-off-by: Amy Parker <[email protected]>

README

@@ -9,6 +9,8 @@ http://storage.webhop.net/documents/interface4.pdf.
 VERSION 4.2 IS INCOMPATIBLE WITH EARLIER VERSIONS OF LCC. DO NOT
 UNLOAD THIS DISTRIBUTION ON TOP OF A 3.X DISTRIBUTION.
 
+LCC is a C89 ("ANSI C") compiler designed to be highly retargetable.
+
 LOG describes the changes since the last release.
 
 CPYRIGHT describes the conditions under you can use, copy, modify, and