oc: Fix typo in docstring

* lisp/oc.el (org-cite-make-insert-processor): Fix typo.

lisp/oc.el

@@ -1540,7 +1540,7 @@ The generated function inserts or edit a citation at point.  More specifically,
 
   On a citation reference:
 
-    - on the prefix or right before th \"@\" character, insert a new reference
+    - on the prefix or right before the \"@\" character, insert a new reference
       before the current one,
     - on the suffix, insert it after the reference,
     - otherwise, update the cite key, preserving both affixes.