Replace `typical_phases.rst` and `examples.rst` with a single `example_synth.rst`.
Also updating the counter example to match.
Aims to reduce redundancy, and simplify the getting started section.
Details on things like `proc`, `memory` and `fsm` should instead be in the advanced section (under the new `synth` subsection).
Code now resides in `docs/source/code_examples`.
`CHAPTER_Prog` -> `stubnets`
`APPNOTE_011_Design_Investigation` -> `selections` and `show`
`resources/PRESENTATION_Intro` -> `intro`
`resources/PRESENTATION_ExSyn` -> `synth_flow`
`resources/PRESENTATION_ExAdv` -> `techmap`, `macc`, and `selections`
`resources/PRESENTATION_ExOth` -> `scrambler` and `axis`
Note that generated images are not yet configured to build from the new code locations.
Krystine Sherwin