tweak examples and doc

README.adoc

@@ -408,10 +408,19 @@ by default, you could add this to the command line:
 When this option is supplied, extra headers may be included with the url payload as part of url generation.
 These extra headers will then be returned as part of the response.
 
-These extra headers are part of a 4th encoded url path component, signed under the hmac signature.
+These extra headers are part of an additional encoded url path component, signed under the hmac signature.
 
-The underlying data is a json dict/map of string values. +
-Example:
+Example standard url format:
+----
+/D23vHLFHsOhPOcvdxeoQyAJTpvM/aHR0cDovL2dvbGFuZy5vcmcvZG9jL2dvcGhlci9mcm9udHBhZ2UucG5n
+----
+
+Example of extra-headers component url format:
+----
+/sYpOByX0byESnG24QMUX5Ac0IXM/aHR0cDovL2dvbGFuZy5vcmcvZG9jL2dvcGhlci9mcm9udHBhZ2UucG5n/eyJjb250ZW50LWRpc3Bvc2l0aW9uIjoiYXR0YWNobWVudDsgZmlsZW5hbWU9XCJpbWFnZS5wbmdcIiJ9
+----
+
+The underlying extra-headers data in the above url path partial is a json dict/map of string values:
 ----
 {
  "content-disposition": "attachment; filename=\"image.png\""

examples/python3-base64.py

@@ -60,7 +60,7 @@ def camo_url(hmac_key, image_url, extra_headers=None):
  camo_url(
  "test",
  "http://golang.org/doc/gopher/frontpage.png",
- {"content-disposition": "attachment; filename=\"image.png\""}
+ {"content-disposition": 'attachment; filename="image.png"'}
  )
 )
 # https://img.example.com/-hNoquWgyjNgzF7HXYyvGwteyLI/aHR0cDovL2dvbGFuZy5vcmcvZG9jL2dvcGhlci9mcm9udHBhZ2UucG5n/eyJjb250ZW50LWRpc3Bvc2l0aW9uIjogImF0dGFjaG1lbnQ7IGZpbGVuYW1lPVwiaW1hZ2UucG5nXCIifQ