docs: Add quick start examples

[adigitoleo]

Adds two quick start examples, one for “normal” plots and one for a map. Maybe the map example can be improved a bit later.

[adigitoleo]

Had to use the gmtend(show = true) to avoid missing output file errors like this one when testing locally, maybe this can be avoided?

[adigitoleo]

Hmm, subplot(:end) followed by gmtend(show = true) produces the missing file error, this was not happening without subplot(:end).

Edit: I'm just removing the gmtbegin/gmtend, it works fine without it.

With current GMT.jl master there seems to be a problem with the region = :global in the map inset.

[adigitoleo]

[joa-quim]

Ok, thanks for the examples and sorry for the lack of information. Some points:

• The Docs repository is now in https://github.com/GenericMappingTools/GMTjl_doc
• The subplot examples must go to https://github.com/GenericMappingTools/GMTjl_doc/tree/master/examples/subplot
• and the inset to https://github.com/GenericMappingTools/GMTjl_doc/tree/master/examples/embellish (I'll put one other example there)

[joa-quim]

With current GMT.jl master there seems to be a problem with the region = :global in the map inset.

Not, you need to end the inset with a inset(:end)

[adigitoleo]

Thanks for the info, I'll move it across. Not sure why the manifest file got commited, that was a mistake.

I was thinking that maybe it could be helpful to have a quick example right away on the front page, what do you think? I can move these to the other sections if you want, maybe there is a better example for the homepage?

[joa-quim]

With the examples tiles so visible in the main page I prefer not to have any quick first plot in the front page.