doc: Consider installing doc/ with make install

[ch4ot1c]

Do we want to make install doc/ into /usr/local/share/doc/bitcoin/ (see docdir in https://www.gnu.org/prep/standards/html_node/Directory-Variables.html)? Currently, man pages are installed to /usr/local/share/man/man1/bitcoin*.

This describes contrib/debian/copyright being placed here as well:
https://www.debian.org/doc/debian-policy/ch-archive.html#copyright-considerations

Furthermore, files like README.md and INSTALL.md could have their extensions removed in the dist-hook.
automake --help has a list of Files automatically distributed if found (e.g. make dist will include):

Files automatically distributed if found (always):
  ABOUT-GNU           INSTALL             config.rpath        ltconfig
  ABOUT-NLS           NEWS                config.sub          ltmain.sh
  AUTHORS             README              depcomp             mdate-sh
  BACKLOG             THANKS              install-sh          missing
  COPYING             TODO                libversion.in       mkinstalldirs
  COPYING.DOC         ar-lib              ltcf-c.sh           py-compile
  COPYING.LESSER      compile             ltcf-cxx.sh         texinfo.tex
  COPYING.LIB         config.guess        ltcf-gcj.sh         ylwrap
  ChangeLog

[ch4ot1c]

Aside:
Currently, some docs expect binaries to be at ./bin/, which isn't true for the source repo / distribution, nor would it be in /usr/local/share/doc/bitcoin/ after make install.

[cvengler]

Concept ACK, the manpages aren't really useful because they are just a help2man

[willcl-ark]

Is this something that we actually want to add? IMO adding a load of (mostly) markdown files to this dir would be clunky at best...

If we don't plan for this then I think we can close the issue.

If we do then it would probably make sense to wait until the cmake project has resolved one way or another before making (low priority) changes to the make process?

[pinheadmz]

This issue is unlikely to be fixed in Bitcoin Core. We'll close for now, but feel free to open another issue or pull request with a fix.