Fixed some documentation typos.

src/lay/doc/programming/database_api.xml

@@ -990,7 +990,7 @@ shapes.each(RBA::Shapes::SBoxes | RBA::Shapes::SPolygons) { |s| ... }</pre>
   </p>
 
   <p>
-  Shapes can be replaced by other primitives using one of the <p>replace</p> methods.
+  Shapes can be replaced by other primitives using one of the <k>replace</k> methods.
   Please note that using "replace" inside an iterator loop may lead to unexpected 
   behavior of the iterator, so modifying a shape inside an iterator loop should be
   avoided. Here is an example:

src/lay/doc/programming/geometry_api.xml

@@ -24,6 +24,11 @@
   for geometrical algorithms like boolean operations and DRC checks.
   </p>
 
+  <p>
+  Most classes of the geometry API provide a hash value so they can be used as keys in Ruby 
+  hashes.
+  </p>
+
   <h2>The Point class</h2>
 
   <keyword name="Point"/>