dev-guide: Emphasize the need to read proxylite instructions carefully (#600)
dev-guide: Emphasize the need to read proxylite instructions carefully (#600)

* dev-guide: Emphasize the need to read proxylite instructions carefully

* dev-guide: Proxy section cleanup

Change the ambiguous pronouns. Reordered the bullet points to align them
with the example.

comptelfwd/dcos-commons,adragomir/dcos-commons,mesosphere/dcos-commons,vishnu2kmohan/dcos-commons,adragomir/dcos-commons,comptelfwd/dcos-commons,mesosphere/dcos-commons,vishnu2kmohan/dcos-commons,comptelfwd/dcos-commons,mesosphere/dcos-commons,vishnu2kmohan/dcos-commons,comptelfwd/dcos-commons,adragomir/dcos-commons,comptelfwd/dcos-commons,comptelfwd/dcos-commons,mesosphere/dcos-commons,adragomir/dcos-commons,mesosphere/dcos-commons,vishnu2kmohan/dcos-commons,vishnu2kmohan/dcos-commons,adragomir/dcos-commons