fix(api-docs): Update api docs for group hash endpoints (#81082)

Splitting out the docs change from
https://github.com/getsentry/sentry/pull/81017.

api-docs/paths/events/issue-hashes.json

@@ -22,6 +22,16 @@
           "type": "string"
         }
       },
+      {
+        "in": "query",
+        "name": "full",
+        "schema": {
+          "type": "boolean",
+          "default": true
+        },
+        "description": "If this is set to true, the event payload will include the full event body, including the stacktrace. Set to 1 to enable.",
+        "required": false
+      },
       {
         "$ref": "../../components/parameters/pagination-cursor.json#/PaginationCursor"
       }