Improve service documentation

[erikbosch]

Describe your changes

This originates from that I found the current documentation somewhat limited. What I have done:

• Updated service tutorial
• Included the examples as source code as well, to make it easier to maintain them
• Removed some junk from templates. I hope we do not need to implement analytics, and we have no good description on what is core features for this repository.
• Adding some general info on how to build and test doc in main readme
• Docsy theme updated
• Now we also build for Pull Requests

Please visit https://erikbosch.github.io/velocitas-docs/ for a rendered version after changes applied

Issue ticket number and link

Checklist before requesting a review

• I have performed a self-review of my code
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics?
• Will this be part of a product update? If yes, please write one phrase about this update.

[MP91]

please check if you could move some general concepts to the title page to not copy'n'paste the same content on 2 pages. The definition of address/port comes to my mind e.g.

[erikbosch]

please check if you could move some general concepts to the title page to not copy'n'paste the same content on 2 pages. The definition of address/port comes to my mind e.g.

I wanted to let

please check if you could move some general concepts to the title page to not copy'n'paste the same content on 2 pages. The definition of address/port comes to my mind e.g.

I think it has a value that the client/server pages are quite independent, and the environment variables you need to set varies partially.

[MP91]

LGTM

Only merge after the SDK PR is merged