Add documentation for close, and context manager for SubscriberClient

[alonme]

The code examples in googleapis.dev do not close the SubscriberClient, and the context manager for this class is not mentioned anywhere, opposed to documenatation in https://cloud.google.com/pubsub/docs/pull .

Not closing the client results in a resource leak, so i think it should be clear from the documentation.

[meredithslota]

@alonme Thank you for the report! Can you point me to where in googleapis.dev the code samples don't match? I took a quick look and couldn't find it. Generally, the code samples in cloud.google.com will be more thorough.

[alonme]

@meredithslota
The code examples in the following pages, create Subscriber instances, however they don't close them.

https://googleapis.dev/python/pubsub/latest/index.html
https://googleapis.dev/python/pubsub/latest/subscriber/index.html

the code examples in cloud.google.com explicitly state the reason why closing is important and use the context manager, which is totally missing from the googleapis.dev docs

[alonme]

@meredithslota @anguillanneuf

any chance this is also missing from the examples of PublisherClient ?

i see that it also has an exit method

python-pubsub/google/pubsub_v1/services/publisher/client.py

Line 1430 in c52aa05

def __exit__(self, type, value, traceback):

does this also create a resource leak?