replace dokkaFatJar with dokkaRuntime

[unlimitedsola]

as per what migrating note says: https://github.com/Kotlin/dokka/wiki/FAQ#migrating-from-older-versions-to-0918

[fbenz]

According to the FAQ, one has to change the way the fat jar is included when migrating to the not yet released version 0.9.19: https://github.com/Kotlin/dokka/wiki/FAQ#migrating-from-older-versions-to-0919
The FAQ does not mention removing the far JAR entirely. So bu just looking at the FAQ, I can not judge whether this is the right thing to do. Is there any other source (e.g. a commit/PR) that shows that this should be done?

[unlimitedsola]

@fbenz sorry I didn't check the version, but one thing I did encounter is when I have multiple dokka task, there's an issue with dokkaFatJar configuration. you can check the issue link: Kotlin/dokka#462

[unlimitedsola]

One more thing worth noting is, even though that migration guide says it's for 0.9.19, but the example configuration in their README file uses dokkaRuntime for 0.9.18 (https://github.com/Kotlin/dokka/blob/master/README.md)

So my opinion would be it's fine to follow the documented example

[fbenz]

This change is done as part of the upgrade to Dokka 0.10.1, see #385