Update README files with Peerunity content

[brossi]

The following files are known to contain outdated information, and need to be updated to include Peerunity-specific content. There are probably other files as well (in addition to the localization template and other files), so if you know of anything that has been missed, please point it out here.

• /README.md
• /doc/README.md
• /doc/README_windows.txt

Q: It may be a better first question to ask if there a reason that the files in the docs directory, README.md and README_windows.txt, actually need to exist? From what I can tell, they serve the same purpose as the build-{OS}.txt files.

[brossi]

Another file that needs to be updated with Peerunity content:

• /doc/readme-qt.rst (still references "bitcoin")
• /doc/translation_process.md (another set of "bitcoin" references)