setup CI and tidy to use typos for spellchecking and fix few typos

compiler/rustc_attr_parsing/src/context.rs

@@ -187,7 +187,7 @@ impl Stage for Late {
     }
 }
 
-/// used when parsing attributes for miscelaneous things *before* ast lowering
+/// used when parsing attributes for miscellaneous things *before* ast lowering
 pub struct Early;
 /// used when parsing attributes during ast lowering
 pub struct Late;