Fix typo and add punctuation

lib/liquid/drop.rb

@@ -2,9 +2,9 @@ module Liquid
 
   # A drop in liquid is a class which allows you to export DOM like things to liquid.
   # Methods of drops are callable.
-  # The main use for liquid drops is the implement lazy loaded objects.
+  # The main use for liquid drops is to implement lazy loaded objects.
   # If you would like to make data available to the web designers which you don't want loaded unless needed then
-  # a drop is a great way to do that
+  # a drop is a great way to do that.
   #
   # Example:
   #
@@ -18,7 +18,7 @@ module Liquid
   #   tmpl.render('product' => ProductDrop.new ) # will invoke top_sales query.
   #
   # Your drop can either implement the methods sans any parameters or implement the before_method(name) method which is a
-  # catch all
+  # catch all.
   class Drop
     attr_writer :context