added back link

RaspberryPiZero_bcm2835/index.html

@@ -69,6 +69,7 @@ int main(int argc, char **argv)
 
 <p>Note: This test was run on a RPiZero W, instead of the baseline version (without wifi).</p>
 
+<p><a href='../index.html'>Back</a></p>
 
 </body>
 

RaspberryPiZero_node_rpio/index.html

@@ -33,6 +33,8 @@ while(1){rpio.write(3, 1-rpio.read(5) ); }
 
 <p>Note: This test was run on a RPiZero W, instead of the baseline version (without wifi).</p>
 
+<p><a href='../index.html'>Back</a></p>
+
 </body>
 
 </html>
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