chore: add mongo to gitignore

Author: joshunrau

.gitignore

@@ -57,4 +57,7 @@ testing/k6/notebooks/
 /misc/
 
 # autogenerated api docs
-apps/outreach/src/content/docs/en/runtime-core-docs/
+apps/outreach/src/content/docs/en/runtime-core-docs/
+
+# mongodb
+mongo/