[Plugin] Add documentation for the VCR plugin

[GaryPEGEOT]

See php-http/vcr-plugin#3

[dbu]

thanks a lot! this documentation already looks very good. i added some suggestions for small improvements.

we could add some cross-referencing between the mock client: http://docs.php-http.org/en/latest/clients/mock-client.html and this page. something like mention in each that the other thing is an alternative for testing.

[GaryPEGEOT]

I've addressed all the comments (unless I forgot one), also added a comment about the responses headers added by both plugins. Might need some proof reading 😄

[dbu]

thanks for the update. one last question:

[dbu]

can you please rebase on master? there was some change in the way we check the doc that made ci failing, i fixed it on master.

[GaryPEGEOT]

can you please rebase on master? there was some change in the way we check the doc that made ci failing, i fixed it on master.

Done!

[dbu]

awesome, cheers!