* Add envoy metrics service protos

This patch imports protos from envoyproxy/data-plane-api and
prometheus/client_model to enable metrics service service feature in
SkyWalking OAP.
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Add Envoy related docs
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Update the LICENSE to include new protos license

From:
- envoyproxy/data-plane-api
- prometheus/client_model
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Add a complete config.yaml example
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Add note on Envoy dynamic config
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Add protoc-gen-validate license
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Add samples
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Make CI and license right.

* Update README.md

@dhi typo :P

* Update README.md

Another typo :P

* Delete metrics.json

metrics.json is included in identify.json and not be linked in document.

* Update user wall.

* Add a missing website.

* Make sure all document images ref from our Apache website.

* Change the statement.

* Update README.md

* Update powered-by.md

* 🎉 PHP agent

* Update powered-by.md

Change user list order

Add 5 new users based on #443

* Update document and user wall.

* Change format.

* user wall updated.

* Fix typo

* Update README.md

* Update Screenshots.md

* Update Screenshots.md

* Update Screenshots.md

* Replace v5 changes by a link to 5.x branch. New v6 changelog.

* Finish query doc and fix a missing field in alarm doc.

* Add link to official oal in alarm doc.

* Fix words.

* Fix some doc

* Update README.md

* Update README.md

* Update README.md

* Update README.md

* Change oal doc.

* Remove typo

* Remove document WIP tag.

* Fix few words.

* no message

* Adjust contribution guides.

Add a lot of documents. @peng-yongsheng @hanahmily . Also @hanahmily , the k8 cluster management document and deploy document need you to add.

* Update users.

* Add a separated use case list

* Update README_ZH.md

* Create use-case-list.md

Add use cases.

* Update README.md

* Update README_ZH.md

* Update README_ZH.md

* Added OpenAPM Badge to readme

* Update README.md

* Added OpenAPM Badge to readme

* Update README.md

Add an announcement for 6.0

Init branch 6.0 for our next big iteration. Change root readme. Format field document in table.  Remove Chinese documents.