Adding first draft of Official Repo Guidelines

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)

(cherry picked from commit 58e89878374d12c916fa9e2b5436f5e042bc6978)

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: SvenDowideit)
Revisions based on feedback.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)

(cherry picked from commit eb8d0c1ccffe612f2c017871d5b8b39320256c6f)

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: SvenDowideit)
Format and typo fixes

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)

(cherry picked from commit a899b8a63ec83bc5fa70ff8663db5ae3671d56a9)

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: SvenDowideit)
More format fixes.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)

(cherry picked from commit 5fea2b5be32165364294e22bc24aee3fa34cf756)

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: SvenDowideit)
More format wrestling.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)

(cherry picked from commit 5b6c4051d58bf535eded3ae557a0996937e96045)

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: SvenDowideit)
Fix formatting, change to markdown block for long

Signed-off-by: Joe Ferguson <joe@infosiftr.com>
(cherry picked from commit bcb9378c5b91f8fd7bc99d1ad0904f5cba6ee613)

Docker-DCO-1.1-Signed-off-by: Joe Ferguson <joe@infosiftr.com> (github: SvenDowideit)
Fixes a couple small typos

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)

(cherry picked from commit a2ba4d56eb134f95eba790bb484e0c8bd77d1fc4)

Conflicts:
	docs/sources/docker-hub/official_repos.md

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: SvenDowideit)
Adding new Dockerfile Best Practices doc, and links thereto.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)

(cherry picked from commit d9fd5f6199aebb9ea784f5b23ec97b960f89f3d4)

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: SvenDowideit)
Typo and formatting fixes. Copy edits.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)

(cherry picked from commit 6747dfc8031205f0e629a3508f14125b3b66a5b2)

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: SvenDowideit)
Revisions and edits based on feedback.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)

(cherry picked from commit 950eccab4ad4d79a5afa154849567ddfdf8dc7eb)

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: SvenDowideit)