missing self in readme example

[bnomei]

the json example in the readme has no self in various params but the json file from the tests does have these set.
https://github.com/paragonie/csp-builder#example
https://github.com/paragonie/csp-builder/blob/e9a7560fd3f133a85f03c51de5fc051ac97630a7/test/vectors/basic-csp.json

for example i am guessing that using the example from the readme does not set self fore base-uri. but that might not be a good example then, right? the resulting csp will not work well.

unless i am misstaken please adjust the readme json example so it will have sensible defaults where self might be needed. thanks.