Added more print statements to greeting function

suggested by @fercer in issue swcarpentry#588

Author: sstevens2

_episodes/16-writing-functions.md

@@ -39,6 +39,8 @@ keypoints:
 ~~~
 def print_greeting():
     print('Hello!')
+    print('The weather is nice today.')
+    print('Right?')
 ~~~
 {: .language-python}