ref-manual, mega-manual: Updated the source fetching figure

Fixes [YOCTO #2808]

Updated the figure to use the "spatula" type version of the
general BitBake box.  Also had to adjust the width a bit to
get the figure to display correctly.

(From yocto-docs rev: 3049e20eb215b00e61dabed9c124fa8ebc6c946b)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/technical-details.xml

@@ -977,7 +977,7 @@
             <para>
                 The first stages of building a recipe are to fetch and unpack
                 the source code:
-                <imagedata fileref="figures/source-fetching.png" align="center" width="6in" depth="4in" />
+                <imagedata fileref="figures/source-fetching.png" align="center" width="6.5in" depth="4in" />
             </para>
 
             <para>