Fix typo in the manual

Change-Id: I1110901c080852b37e70a111e55c35c7f2b4e6d7
diff --git a/manual/configure_rockbox/system_options.tex b/manual/configure_rockbox/system_options.tex
index 30a3237..2b5404a 100644
--- a/manual/configure_rockbox/system_options.tex
+++ b/manual/configure_rockbox/system_options.tex
@@ -220,7 +220,7 @@
     These settings control the functions of touchpad devices.
     \begin{description}
     \opt{SANSA_FUZEPLUS_PAD,GIGABEAT_PAD}{
-      \item [Touchpad Senstivity. ]This setting controls the amount of pressure needed to
+      \item [Touchpad Sensitivity. ]This setting controls the amount of pressure needed to
       register a touchpad press. If set to \opt{SANSA_FUZEPLUS_PAD}{\setting{25}}\opt{GIGABEAT_PAD}
       {\setting{High}} the lightest touch will register. If set to \opt{SANSA_FUZEPLUS_PAD}
       {\setting{-25}}\opt{GIGABEAT_PAD}{\setting{Normal}} a firmer press will be needed to register