Added link to next step

Linked 4_point_to_new_platform.md to the next step 5_test_all_the_things.md
Added link to next step

Added a link from the 5th step of the plan (5_test_all_the_things.md) to the 6th (6_enable_external_access.md)
Added link to next step

Added a link from the 6th step (6_enable_external_access.md) to the 7th (7_monitor_for_regressions.md)
Merge pull request #1 from kalbir/adding_links_to_later_steps

Adding links to later steps