Fix checkout & build instructions

* CONTRIBUTING: Fix Git repository url.
	* doc/website/mainpage.txt: Add elfutils into the dependencies
	list and fix the repository directory name.  Also use autoreconf
	-i.
	* include/abg-fwd.h: Fix Git repository URL.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>

CONTRIBUTING

@@ -1,7 +1,7 @@
 The project homepage is at https://sourceware.org/libabigail
 
 The current libabigail source code can be checked out with:
-git clone git://git.sourceware.org/git/libabigail
+git clone git://sourceware.org/git/libabigail
 
 The mailing list to send messages and patches to is
 libabigail@sourceware.org.

doc/website/mainpage.txt

@@ -48,13 +48,14 @@ the moment the dependencies are the following Free Software packages:
     \li <a href="http://www.xmlsoft.org">libxml2</a>
     \li <a href="http://www.gnu.org/software/autoconf/">autoconf</a>
     \li <a href="http://www.nih.at/libzip">libzip</a>
+    \li <a href="https://fedorahosted.org/elfutils/">elfutils</a>
 
 Then go to your local libabigail.git directory where the source code
 you've checked out lies and create a 'build' directory that will
 receive the binaries resulting from the compilation:
 
 \code{.sh}
-    cd libabigail.git
+    cd libabigail
     mkdir build
 \endcode
 
@@ -62,7 +63,7 @@ Generate the relevant build-system-related information needed to
 configure the package for compilation, by typing:
 
 \code{.sh}
-    autoreconf
+    autoreconf -i
 \endcode
 
 Then configure the package:

include/abg-fwd.h

@@ -51,7 +51,7 @@ namespace abigail
    href="http://sourceware.org/libabigail"> here</a>.
 
    The current libabigail source code can be checked out with:
-   git clone git://git.sourceware.org/git/libabigail.git.
+   git clone git://sourceware.org/git/libabigail.git.
 
    The mailing list to send messages and patches to is
    libabigail@sourceware.org.