misc nameres changes for anon consts

compiler/rustc_error_codes/src/error_codes/E0771.md

@@ -1,9 +1,11 @@
+#### Note: this error code is no longer emitted by the compiler
+
 A non-`'static` lifetime was used in a const generic. This is currently not
 allowed.
 
 Erroneous code example:
 
-```compile_fail,E0771
+```compile_fail,E0770
 #![feature(adt_const_params)]
 
 fn function_with_str<'a, const STRING: &'a str>() {} // error!