[patrickwehbe]

Changes

The "Limiting concurrency" example in docs/fileio.rst uses async with open_file('/foo/bar', limiter=limiter) as fp:. Since open_file() is a coroutine function, this raises TypeError: 'coroutine' object does not support the asynchronous context manager protocol when run as written.

Added the missing await so the example actually runs. It now matches the other two open_file() examples in the same file, which already use async with await open_file(...).

Checklist

If this is a user-facing code change, like a bugfix or a new feature, please ensure that
you've fulfilled the following conditions (where applicable):

• You've added tests (in tests/) which would fail without your patch
• You've updated the documentation (in docs/), in case of behavior changes or new
  features
• You've added a new changelog entry (in docs/versionhistory.rst).

If this is a trivial change, like a typo fix or a code reformatting, then you can ignore
these instructions.

[agronholm]

Thanks.