docs - updates Linkedin example to follow new tested pattern

[jtroussard]

Updating the Linkedin example so that it follows the new pattern provided by #530

[jtroussard]

@JonathanHuot might need some guidance on the scope of the unit test, also maintainer access to the vault might be more granular, however I have not tried to push anything to secrets using the cli yet.

[coveralls]

coverage: 90.097%. remained the same when pulling cf7420d9ee8a9f87e615d833ede94bafcd4d38ee on docs-examples-linkedin into 77905a471c7931835525228675ac60eae39bec3f on master.