docs(readme): fix misplaced period (#667)

Author: stainless-app[bot]

README.md

@@ -442,7 +442,7 @@ with Lithic() as client:
 This package generally follows [SemVer](https://semver.org/spec/v2.0.0.html) conventions, though certain backwards-incompatible changes may be released as minor versions:
 
 1. Changes that only affect static types, without breaking runtime behavior.
-2. Changes to library internals which are technically public but not intended or documented for external use. _(Please open a GitHub issue to let us know if you are relying on such internals)_.
+2. Changes to library internals which are technically public but not intended or documented for external use. _(Please open a GitHub issue to let us know if you are relying on such internals.)_
 3. Changes that we do not expect to impact the vast majority of users in practice.
 
 We take backwards-compatibility seriously and work hard to ensure you can rely on a smooth upgrade experience.