Fix docs in data_filter_example

[Alejandro Wainzinger]

The below examples won't work because the method verb isn't capitalized, but it is in the rego. Should be a simple fix to change get to GET. Will submit PR if time later.

contrib/data_filter_example/data_filter_example/opa.py

Lines 40 to 59 in bcd146f

 >>> result = opa.compile(q='data.example.allow==true', input={'method':'get', 'path': ['posts'], 'user': 'bob'}, unknowns=['posts']) 
  
 The result will contain the SQL clauses to apply to your query. 
  
 >>> result.sql.clauses[0].sql() 
 u'WHERE (("bob" = posts.author))' 
  
 On the other hand if the query is NEVER defined, the `defined` attribute will 
 be False. 
  
 >>> result = opa.compile(q='data.example.allow==true', input={'method':'get', 'path': ['deadbeef'], 'user': 'bob'}, unknowns=['posts']) 
 >>> result.defined 
 False 
  
  
 The last part of the policy says that super users can access the API 
 unconditionally. In this case, the `defined` attribute will be True but the 
 `sql` attribute will be None. 
  
 >>> result = opa.compile(q='data.example.allow==true', input={'method':'get', 'path': ['deadbeef'], 'user': 'bob'}, unknowns=['posts']) 

[Torin Sandall]

@xevix nice catch. If you have a fix you can submit, that would be great. I'm going to mark this as help-wanted since I think this is an easy for anyone to contribute.