Extend README, add basic user guide

[sebkur]

Signed-off-by: Sebastian Kürten sebastian@topobyte.de

[sebkur]

See a rendered version of the changes here: https://github.com/sebkur/proj4j/tree/improve-docs

[pomadchin]

Hey @sebkur! Thanks for a cool PR. How do you feel about putting that quick user guide directly into the README.md?

[sebkur]

My primary intention was to add an example as it took me a few minutes to get some working code and would have liked to see some examples that let me dive right in.

In the process of doing that, I compared the current README.md to the one from JTS and figured there are a bunch of other things that should probably be there and added some of the obvious things:

• state connection to LocationTech
• linkify contribution guide
• add user guide
• in the user guide:
  • add explanation how to use on Maven
  • add explanation how to use on Gradle
  • add examples

[sebkur]

Hey @sebkur! Thanks for a cool PR. How do you feel about putting that quick user guide directly into the README.md?

yeah, seems like a good idea. Unless the main README gets too long, I think it would fit there quite well

[pomadchin]

@sebkur somewhere above the Building, Testing and installing locally section probably?

[pomadchin]

Thanks for doing that hard work! Everyone always forgets about docs, that's a big problem.

[sebkur]

Ok, pushed a new version

[sebkur]

thanks for the quick response!