fix typo reported by aggraef

pd/doc/1.manual/x5.htm

@@ -1804,7 +1804,7 @@ stroke and fill color.
 
 <P> Object and message boxes are sized exactly the same on all platforms.
 On some platforms with suboptimal font renderers this means there will be
-some padding at the right of the of the box. This keeps the users on those
+some padding at the right of the box. This keeps the users on those
 platforms from positioning the boxes so close that they cause collisions
 on all the other systems. In Pd Vanilla boxes are sized to fit tightly
 around the text.