Improve Capture filter documentation

[XAMPPRocky]

I think it would be awesome to show in capture.md under "Configuration Examples" that you could do first 3 values capturing using prefix, but also do the same thing using regex -- two different ways to do the same thing, just to give people ideas of what is possible.

Originally posted by @markmandel in #458 (comment)

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I would also we should add links to the regex syntax, and the caveats of the differences between the regular on bytes regex.