Add release doc for further release process. (#16)

CHANGES.md

-#Changes
+# Changes
 
 ## 0.1.0
 1. Establish the LUA tracing core.

README.md

@@ -135,11 +135,8 @@ Create 2 kinds of span
 * Join `skywalking` channel at [Apache Slack](https://join.slack.com/t/the-asf/shared_invite/enQtNzc2ODE3MjI1MDk1LTAyZGJmNTg1NWZhNmVmOWZjMjA2MGUyOGY4MjE5ZGUwOTQxY2Q3MDBmNTM5YTllNGU4M2QyMzQ4M2U4ZjQ5YmY). If the link is not working, find the latest one at [Apache INFRA WIKI](https://cwiki.apache.org/confluence/display/INFRA/Slack+Guest+Invites).
 * QQ Group: 392443393(2000/2000, not available), 901167865(available)
 
-# Release Tar Build
-```shell
-> export VERSION=x.y.z
-> make release-src
-```
+# Relase Guide
+All committers should follow [Release Guide](release.md) to publish the official release.
 
 # License
 Apache 2.0

release.md

+# Release Guide
+All committer should follow these steps to do release for this repo.
+
+1. Update the [CHANGES.md](CHANGES.md) to prepare the official release. 
+
+2. Package the source release.
+
+```shell
+> export VERSION=x.y.z
+> make release-src
+```
+
+Use SVN to upload the files(tgz, asc and sha512) in the `release` folder to `https://dist.apache.org/repos/dist/dev/skywalking/nginx-lua/x.y.z`.
+
+3. Make the internal announcements. Send an announcement mail in dev mail list.
+
+```
+[ANNOUNCE] SkyWalking Nginx LUA x.y.z test build available
+
+The test build of x.y.z is available.
+
+This is our Apache release.
+We welcome any comments you may have, and will take all feedback into
+account if a quality vote is called for this build.
+
+Release notes:
+
+ * https://github.com/apache/skywalking-nginx-lua/blob/vx.y.z/CHANGES.md
+
+Release Candidate:
+
+ * https://dist.apache.org/repos/dist/dev/skywalking/nginx-lua/x.y.z/
+ * sha512 checksums
+   - xxxxxxx  skywalking-nginx-lua-x.y.z-src.tgz
+
+Release Tag :
+
+ * vx.y.z
+
+Release CommitID :
+
+ * https://github.com/apache/skywalking-nginx-lua/tree/xxxxxxxxxx
+
+Keys to verify the Release Candidate :
+
+ * https://dist.apache.org/repos/dist/release/skywalking/KEYS
+
+
+A vote regarding the quality of this test build will be initiated
+within the next couple of days.
+```
+
+4. Wait at least 48 hours for test responses. If there is a critical issue found and confirmed by the PMC, this release should be cancelled.
+
+5. Call for a vote. Call a vote in dev@skywalking.apache.org
+
+```
+[VOTE] Release SkyWalking Nginx LUA x.y.z 
+
+This is a call for vote to release Apache SkyWalking Nginx LUA version x.y.z.
+
+Release notes:
+
+ * https://github.com/apache/skywalking-nginx-lua/blob/vx.y.z/CHANGES.md
+
+Release Candidate:
+
+ * https://dist.apache.org/repos/dist/dev/skywalking/nginx-lua/x.y.z/
+ * sha512 checksums
+   - xxxxxxx  skywalking-nginx-lua-x.y.z-src.tgz
+
+Release Tag :
+
+ * vx.y.z
+
+Release CommitID :
+
+ * https://github.com/apache/skywalking-nginx-lua/tree/xxxxxxxxxx
+
+Keys to verify the Release Candidate :
+
+ * https://dist.apache.org/repos/dist/release/skywalking/KEYS
+
+
+A vote regarding the quality of this test build will be initiated
+within the next couple of days.
+```
+
+5. Publish release, if vote passed.
+
+Move the release from RC folder to the dist folder. This will begin the file sync across the global Apache mirrors.
+```
+> export SVN_EDITOR=vim
+> svn mv https://dist.apache.org/repos/dist/dev/skywalking/nginx-lua/x.y.z https://dist.apache.org/repos/dist/release/skywalking/nginx-lua
+....
+enter your apache password
+....
+
+Send ANNOUNCE mail to dev@skywalking.apache.org
+```
+Mail title: [ANNOUNCE] Release Apache SkyWalking Nginx LUA version x.y.z
+
+Mail content:
+Hi all,
+
+Apache SkyWalking  Team is glad to announce the first release of Apache SkyWalking Nginx LUA x.y.z
+
+SkyWalking: APM (application performance monitor) tool for distributed systems, 
+especially designed for microservices, cloud native and container-based (Docker, Kubernetes, Mesos) architectures. 
+
+SkyWalking Nginx Agent provides the native tracing capability for Nginx powered by Nginx LUA module.
+
+Vote Thread: 
+
+Download Links : http://skywalking.apache.org/downloads/
+
+Release Notes : https://github.com/apache/skywalking-nginx-lua/blob/vx.y.z/CHANGES.md
+
+Website: http://skywalking.apache.org/
+
+SkyWalking Resources:
+- Issue: https://github.com/apache/skywalking/issues
+- Mailing list: dev@skywalkiing.apache.org
+- Documents: https://github.com/apache/skywalking-nginx-lua/tree/vx.y.z
+
+
+- Apache SkyWalking Team
+- ```
\ No newline at end of file