Fix typo

Co-authored-by: Who? Me?! <[email protected]>

Author: LeSeulArtichaut

src/identifiers.md

@@ -27,7 +27,7 @@ like macro expansion and name resolution.
 The HIR uses a bunch of different identifiers that coexist and serve different purposes.
 
 - A [`DefId`], as the name suggests, identifies a particular definition, or top-level
-  item, in a given grate. It is composed of two parts: a [`CrateNum`] which identifies
+  item, in a given crate. It is composed of two parts: a [`CrateNum`] which identifies
   the crate the definition comes from, and a [`DefIndex`] which identifies the definition
   within the crate. Unlike [`NodeId`]s, there isn't a [`DefId`] for every expression, which
   makes them more stable across compilations.