Wrong document in cors.md

[Peng]

• Expected behaviour:
  Set CORS header correctly according to the document https://github.com/claudiajs/claudia-api-builder/blob/master/docs/cors.md

• What actually happens:
  CORS headers are not set correctly.

• What's the problem:
  The document says to check:

/claudiajs.com$/.test(request.headers.Origin)

Actually it should check:

/claudiajs.com$/.test(request.normalizedHeaders.origin)

which is documented correctly here: https://github.com/claudiajs/example-projects/blob/master/web-api-custom-cors/web.js

[Gojko Adzic]

thanks, updated