doc: fix README

Signed-off-by: Julien Danjou <julien@danjou.info>

README

@@ -15,10 +15,12 @@ In order to build awesome itself, you need header files and libs of:
   - dbus (optional, use --with-dbus=no with ./configure to disable)
   - gperf
 
-In order to build the awesome man pages, you need these tools:
+In order to build the awesome man pages and documentation,
+you need these tools:
   - asciidoc (recent version)
   - xmlto (recent version)
   - docbook XSL stylesheets
+  - luadoc
 
 In order to build the source code reference, you need these tools:
   - doxygen
@@ -26,21 +28,12 @@ In order to build the source code reference, you need these tools:
 
 Building and Installation
 -------------------------
-If building from git sources, run "./autogen.sh". When autoreconf has
+After extracting the dist tarball, run:
-finished, you can follow the following instructions for building a dist
-tarball.
 
-After extracting the dist tarball, run "./configure --help" and figure out
+  cmake .
-what you might want to adapt for your system. Then run ./configure with the
-proper parameters, and build and install:
-
-  ./configure [...]
   make
   make install # might need root permissions
 
-If you're using gcc as your compiler and do not want awesome's default set
-of warning flags, add AWESOME_CFLAGS="" to your "make" lines.
-
 The source code reference can be built with "make doc".
 
 Running awesome