Rename Pentagon.geo to pentagon.geo

Author: yiyuef

models/Pentagon.geo models/pentagon.geomodels/Pentagon.geo renamed to models/pentagon.geo

@@ -153,4 +153,4 @@ Save "pentagon_mesh.msh";
 // `CombinedBoundary' operators.
 //
 // See e.g. `t16.geo', `t18.geo', `t19.geo' or `t20.geo' for complete examples
-// based on OpenCASCADE, and `examples/boolean' for more.
+// based on OpenCASCADE, and `examples/boolean' for more.