fix a typo

Author: amin1377

libs/librrgraph/src/io/rr_graph.xsd

@@ -37,7 +37,6 @@
        attribute should be the name of a xs:simpleType that defines an
        xs:restriction / xs:enumeration.  This will be demonstrated later.
   -->
-
   <xs:complexType name="channel">
     <xs:attribute name="chan_width_max" type="xs:int" use="required"/>
     <xs:attribute name="x_min" type="xs:int" use="required"/>