Added examples to README file

README

@@ -8,16 +8,24 @@ Installation
 ============
     $ pip install pycksum
 
-    $ easy_install pycksum
-
 Examples
 =====
-.. code-block: python
+The simplest way to use pycksum is to just give it a string:
+
+import pycksum
+ck = pycksum.cksum("Any string")
 
-    import pycksum
-    pycksum.cksum("Any string")
+You can pass in a file or an iterable:
 
+ck = pycksum.cksum( open("filename"))
 
+ck = pycksum.cksum( ["This", "love", "is", "taking", "its", "toll", "on me"])
 
+If you have a lot of data to process, it's more memory-efficient to calculate the cksum incrementally:
 
+c = pycksum.Cksum()
+for data in input_fd:
+    c.add(data)
+ck = c.get_cksum()
+sz = c.get_size()