Remove old upgrade guide

(cherry picked from commit 7e2d5dca12369d9bad626fbbc2fb860a7ccf9a61)
Upgrade guide to 3.6.

(cherry picked from commit d3f9d30a4a8d866c2e850aa3131e95a73db676d0)
(cherry picked from commit ff26917994c6357f280ce4743c8c5b9a66248a29)
(cherry picked from commit a6483af8ca4f793b9b09b9241605416f0aba71ae)
(cherry picked from commit dd9fc32db8854d91b656a1b8c82edc2284aefe38)
(cherry picked from commit 08d9c37ee868f760c51098ee95875722ed5fd041)
(cherry picked from commit 6cb7dfb6d2c473c75c8e75f74239c01f35b35ae8)