Add project documentation to the top level README

This will help people getting the source from git, or downstream
packagers on how to build from source or interact with the
maintainers.

README

@@ -1,5 +1,112 @@
-This is dpkg, Debian's package maintenance system.
+dpkg - Debian's package maintenance system
 
-The primary interface for the dpkg suite is the `dselect' program;
+The primary interface for the dpkg suite is the ‘dselect’ program;
 a more low-level and less user-friendly interface is available in
-the form of the `dpkg' command.
+the form of the ‘dpkg’ command.
+
+
+Releases
+--------
+
+The current legacy, stable and development releases can be found at:
+
+  <http://ftp.debian.org/debian/pool/main/d/dpkg/>
+
+For older releases check:
+
+  <http://snapshot.debian.org/package/dpkg/>
+
+
+Mailing List
+------------
+
+The subscription interface and web archives can be found at:
+
+  <http://lists.debian.org/debian-dpkg/>
+
+The mailing list address is:
+
+  debian-dpkg@lists.debian.org
+
+
+Source Repository
+-----------------
+
+  <http://anonscm.debian.org/gitweb/?p=dpkg/dpkg.git>
+  <git://anonscm.debian.org/dpkg/dpkg.git>
+
+
+Building from git source
+------------------------
+
+To prepare the source tree before starting the build process, some software
+needs to be installed, additional software might provide optional features.
+
+The minimum software required to build dpkg is:
+
+  C89 compiler with few C99 extensions (see doc/coding-style.txt)
+  GNU make
+  GNU autoconf >= 2.60
+  GNU automake >= 1.8
+  GNU gettext  >= 0.18
+  pkg-config
+  flex
+  perl
+
+To run the test suite («make check»):
+
+  TimeDate perl module
+  IO-String perl module
+
+To enable optional functionality or programs, this software might be needed:
+
+  zlib (used instead of the command-line tool)
+  liblzma (from the xz project; used instead of the command-line tool)
+  libbzip2 (from the bzip2 project; used instead of the command-line tool)
+  libselinux (needed for SELinux support)
+  curses compatible library (needed for dselect)
+
+To enable translated or additional («make doc») documentation this
+software will be needed:
+
+  po4a >= 0.36.4
+  pod2man
+  doxygen
+  dot
+
+To enable code coverage («./configure --enable-coverage; make coverage»)
+this software is needed:
+
+  lcov (from the Linux Test Project)
+  Devel-Cover perl module
+
+
+After installing the needed software, and running the following command on
+the git tree:
+
+  $ autoreconf -f -i
+
+the source should be equivalent to the distributed tar source.
+
+
+Building from tar source
+------------------------
+
+The instructions to build the distributed source are included in the
+INSTALL file.
+
+The following configure options might be of interest to disable specific
+programs:
+
+  --without-dselect
+  --without-start-stop-daemon
+  --without-update-alternatives
+  --without-install-info
+
+And the following to disable modifications to the build flags:
+
+  --disable-compiler-warnings
+  --disable-compiler-optimisations
+  --disable-linker-optimisations
+
+To see all available configuration options please run «./configure --help».