This PR migrates the current INSTALL.md to an rst file and then includes it in the documentation. It also does some minor improvements to this file, in particular it now mentions --dep-path
This PR adds (most of) the existing examples to the documentation, and does some other minor updates on the documentation. Some details:
- for consistency, all cpp examples are moved from examples/api to examples/api/cpp
- add capabilities for SMT-LIB examples, and two simple smt2 examples
- more docs/examples/*.rst files
- two new documentation categories: installation (how to obtain, compile and install cvc5) and binary (about the cvc5 binary)
