Corrected typo '%Play' with 'Play' on line 407

Change-Id: I19b290c6dd305537746a2f3abeee947cec53aba9
Reviewed-on: http://gerrit.rockbox.org/324
Reviewed-by: Alex Parker <rockbox@aeparker.com>

manual/advanced_topics/main.tex

@@ -404,7 +404,7 @@ For tags with multiple values, like Play status, the conditional can hold a
 list of alternatives, one for each value the tag can have.
 Example enumeration: 
 \begin{example}
-     \%?mp{\textless}Stop{\textbar}\%Play{\textbar}Pause{\textbar}Ffwd{\textbar}Rew{\textgreater}
+     \%?mp{\textless}Stop{\textbar}Play{\textbar}Pause{\textbar}Ffwd{\textbar}Rew{\textgreater}
 \end{example}
 
 The last else part is optional, and will be displayed if the tag has no value.