docs: mention that libncursesw5-dev is needed for building from git

In addition, tweak some of the wording.

README.GIT

-INSTRUCTIONS TO COMPILE AND INSTALL NANO GIT VERSIONS
-=====================================================
+INSTRUCTIONS FOR COMPILING AND INSTALLING NANO FROM GIT
+=======================================================
 
-The latest version of GNU nano is available via git, but building this needs
-a bit more care than the official stable and unstable tarballs.
+The latest changes and fixes for GNU nano are available via git, but
+building this needs a bit more care than the official tarballs.
 
 
 Prerequisites
 -------------
 
-To successfully compile GNU nano from the git repo, you'll need the following
+To successfully compile GNU nano from git, you'll need the following
 packages:
 
 - autoconf    (version >= 2.61)
 - automake    (version >= 1.7)
+- autopoint   (version >= 0.11.5)
 - gettext     (version >= 0.11.5)
 - git         (version >= 2.7.4)
 - groff       (version >= 1.12)
 - pkg-config  (version >= 0.22)
 - texinfo     (version >= 4.0)
-- glib 2.x    (in case your system doesn't have vsnprintf(), which the
-               configure script will check for)
-- make, gcc, and
-- the normal development libraries (curses or slang, etc.)
+- gcc         (any version)
+- make        (any version)
+
+If you want UTF-8 support, you will also need libncursesw5-dev installed
+(version >= 5.7, or something equivalent if you use --with-slang).
+If your system doesn't have 'vsnprintf' (which the configure script will
+check for), you will also need glib-2.x installed.
 
 These should all be available in your distro's package manager or software
-center, or otherwise on any GNU mirror.  Note that you'll need a version of
-curses or slang with wide character support if you want nano to use UTF-8.
+center, or otherwise on any GNU mirror.
 
 
 Download the source
 -------------------
 
-To obtain the current nano development code (called 'master', or sometimes
-'trunk'), use the following command.  It will create a copy of the files in
-a subdirectory of your current working directory called 'nano':
+To obtain the current nano development branch (called 'master'), use the
+following command.  It will create in your current working directory a
+subdirectory called 'nano' containing a copy of all of the files:
 
     $ git clone git://git.savannah.gnu.org/nano.git nano