THRIFT-5164: Small cleanup on the example code

[fishy]

Client: go

Godoc requires at least one other exported type/function to render the
whole example file in the example, so export
simpleProcessorLoggingMiddleware to make the example of
ProcessorMiddleware more helpful.

Currently it's rendered in a not very helpful way:
https://pkg.go.dev/github.com/apache/thrift@v0.13.1-0.20200430141240-5cffef964a08/lib/go/thrift?tab=doc#example-ProcessorMiddleware

Compare to the client middleware example rendering:
https://pkg.go.dev/github.com/apache/thrift@v0.13.1-0.20200430141240-5cffef964a08/lib/go/thrift?tab=doc#example-ClientMiddleware

While I'm here, also update CHANGES.md to mention ClientMiddleware.

• Did you create an Apache Jira ticket? (not required for trivial changes)
• If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• Did you squash your changes to a single commit? (not required, but preferred)
• Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"?
• If your change does not involve any code, add [skip ci] at the end of your pull request to free up build resources.

[skip ci]

[fishy]

@dcelasun @pacejackson :)

[fishy]

[skip ci] doesn't seem to work 😬

[dcelasun]

[skip ci] doesn't seem to work 😬

I've killed the build, but there is no [skip ci] in the commit body 🙂

[fishy]

The instruction says pull request, it didn't say commit message:

add [skip ci] at the end of your pull request to free up build resources.

[dcelasun]

The instruction says pull request, it didn't say commit message

Ah, that's unfortunate. Fixed by 4873068.

[pacejackson]

👍

[fishy]

Added [skip ci] to the commit message.