Deploy main branch automaticallly to production:

- https://docs.picodata.io/picodata/

Add a manual job for deploying dev branches to staging:

- https://docs.binary.picodata.io/picodata/branch-<branch>

Also setup cache instead of artifacts

It is the most error-prone part ot the documentation, so we need
to check svg references every time we push MR. Also, added a Makefile
to simplify local development.