* Add more details on the project directory structure.
* Add information on contributions and donations.
* Move contributors to the manual but keep a reference.
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>
Make sure that the Markdown syntax already used in the README file is
recognized by repository browsers such as cgit or GitHub.
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>
