add faq and troubleshooting entry regarding insecure response

[GGAlanSmithee]

Regarding #296

Not sure if I interpreted the issues corectly. Added to both FAQ and troubleshooting, since it's not really clear where it should be. Let me know if you want anything changed @NekR

[NekR]

Hey! I believe I meant only troubleshooting part, but I'm totally fine with having relativePaths explanation in FAQ 👍

About troubleshooting section. I think we need to say something about that serviceworker/appcache files might be generated into a wrong directly. I know it's partially implied by "see FAQ about relativePaths" but would be good to make it clearer. E.g. "also make sure that ServiceWorker and/or AppCache files are generated into a right folder. You may use ServiceWorker.output and AppCache.output to change output of the files. See options for details."

Also can you rename serviceworker.js to sw.js since sw.js is the default naming. Just to not confuse people.

@GGAlanSmithee Great work as always! Your help is very appreciated. Thanks! 👌 👏

[NekR]

Oh, also, any idea why tests are failing with this simple docs PR? Looks like AppVeyor issue/glitch.

[GGAlanSmithee]

@NekR thanks for the excellent feedback I will fix it tomorrow if I find time :) also, I will try to make more contributions 👍

[NekR]

Added you to 4.9.0 release notes: https://github.com/NekR/offline-plugin/releases/tag/v4.9.0

Sorry I forgot to do so initially :-(

[GGAlanSmithee]

@NekR fixed your comment - sorry for the delay!

Added you to 4.9.0 release notes: https://github.com/NekR/offline-plugin/releases/tag/v4.9.0

Thanks! Very kind of you. 🙇

[GGAlanSmithee]

Have merged latest master into this. Will merge since you've OK:ed it before @NekR. The problem with the CI will be resolved when #436 is merged, will wait until then.