Slightly clarify how to compile from source

[Miepee]

See title.

[cristian64]

I wish GitHub's markdown had a way to provide a title for code blocks; Phabricator has this. I opted for adding an inline comment in each of the code blocks, but I considered (and still consider) adding a line in bold/italics (or both) as well.

[Miepee]

You can probably fake a title with headers
Something like

For Windows

echo "hi"

For Unix/MacOS

echo "hi"

[cristian64]

It looks good, but TOCs would pick them up, so not ideal. Plain bold style would be better in that case, I think.

[Miepee]

@cristian64 is there any interest in this PR still?

[cristian64]

With Python often considered an interpreted language that runs in a Python interpreter, I wasn't too sure about the use of "compile" in the heading. For what is worth, I don't think it would matter much to those that dare to check out the code.