updated docs

docs/docs/optimization.xml

@@ -141,8 +141,8 @@
          <file>dlib/optimization.h</file>
          <spec_file link="true">dlib/optimization/optimization_line_search_abstract.h</spec_file>
          <description>
-            This function finds the 3rd degree polynomial that interpolates a 
-            set of points and returns you the minimum of that polynomial.
+            This function finds the 2nd or 3rd degree polynomial that interpolates a 
+            pair of points and returns you the minimum of that polynomial.
          </description>
                                  
       </component>