Update check method docs

[bwatters-r7]

Internally and in reviews, we tell contributors not to use fail_with because we should always do our best to make sure a check method returns a check code. I noticed that #18283 had a fail_with and went to pull the relevant citation in our documentation and found it was not there. This just adds the guidance and reasoning not to exit a check method without returning a check code.

[bcoles]

There's an additional historical reason behind not using fail_with, in that module check should never output anything except the CheckCode unless verbose output is enabled.

https://docs.metasploit.com/docs/development/developing-modules/guides/how-to-write-a-check-method.html#check-method-output

[cgranleese-r7]

Looks good to me 👍

[cgranleese-r7]

Release Notes

This PR updates the how-to-write-a-check-method docs to now better explain to not use fail_with as it's best practice to make sure a check method returns a check code.