add docs/libtorrent_plugins.{rst,html} to makefile build system
add docs/libtorrent_plugins.{rst,html} to makefile build system

mildred/rasterbar-libtorrent,mildred/rasterbar-libtorrent,mrmichalis/libtorrent-code,mildred/rasterbar-libtorrent,mrmichalis/libtorrent-code,mrmichalis/libtorrent-code,mildred/rasterbar-libtorrent,mildred/rasterbar-libtorrent,mrmichalis/libtorrent-code,mrmichalis/libtorrent-code,mrmichalis/libtorrent-code,mildred/rasterbar-libtorrent