Fix small typo in testimonial (#1024)

about/people/feeds/testimonials/6400-zarl-zierl.en.xml

@@ -7,7 +7,7 @@
       Johannes Zarl-Zierl (IT Professional)
     </name>
     <text>
-      I bacame a supporter of the FSFE because I'm seeing more and more that writing free
+      I became a supporter of the FSFE because I'm seeing more and more that writing free
       code is ultimately not enough to foster a culture where Free Software is
       seen as an integral part of society. Free software should not be a fringe
       topic supported solely by geeks.