Fix typo in Maintainers Guide
@@ -201,7 +201,7 @@ When making incompatible changes, we should follow the process:
To rename a function parameter, add the `@deprecate_parameter` decorator near
the top after the `@fmt_docstring` decorator but before the `@use_alias`
-decorator (if those two exists). Here is an example:
+decorator (if those two exist). Here is an example:
```
@fmt_docstring
