fix degrees char formatting in man page

fixes issue #64, thanks to @mariobl for the patch.

src/thinkfan.1

@@ -47,7 +47,7 @@ syntax.
 .SS SIMPLE MODE
 In simple mode, Thinkfan uses only the highest temperature found in the
 system. That may be dangerous, e.g. for hard disks.  That's why you should
-provide a correction value (i.e. add 10\-15 °C) for the sensor that has the
+provide a correction value (i.e. add 10\-15 \[char176]C) for the sensor that has the
 temperature of your hard disk (or battery...). See the example config files
 for details about that.
 .SH CONFIGURATION