ZOOKEEPER-3375: Docs enhancements for 3.5 release

I need this PR to be merged to 3.5 before creating a new RC.

- Backport latest release notes to 3.5
- Added comments on compiling with Java 8

Author: Andor Molnar <andor@apache.org>

Reviewers: andor@apache.org

Closes #928 from anmolnar/ZOOKEEPER-3375 and squashes the following commits:

bdb828194 [Andor Molnar] ZOOKEEPER-3375. Some styling fixes
186ce54bc [Andor Molnar] ZOOKEEPER-3375. Backported release notes to 3.5. Added comments on compiling with Java 8.

Conflicts:
	zookeeper-docs/src/main/resources/markdown/releasenotes.md

README.md

@@ -9,8 +9,7 @@ and our wiki, at:
 
    https://cwiki.apache.org/confluence/display/ZOOKEEPER
 
----------------------------
-Packaging/release artifacts
+## Packaging/release artifacts
 
 Either downloaded from https://zookeeper.apache.org/releases.html or
 found in zookeeper-assembly/target directory after building the project with maven.
@@ -35,7 +34,12 @@ is voted on and approved by the Apache ZooKeeper PMC:
 
   https://repo1.maven.org/maven2/org/apache/zookeeper/zookeeper/
 
-# Contributing
+## Java 8
+
+If you are going to compile with Java 1.8, you should use a
+recent release at u211 or above. 
+
+## Contributing
 We always welcome new contributors to the project! See [How to Contribute](https://cwiki.apache.org/confluence/display/ZOOKEEPER/HowToContribute) for details on how to submit patch through pull request and our contribution workflow.
 
 

zookeeper-docs/src/main/resources/markdown/releasenotes.md

@@ -16,6 +16,9 @@ limitations under the License.
 
 # Release Notes - ZooKeeper - Version 3.5.5
 
+Java 8 users: if you are going to compile with Java 1.8, you should use a
+recent release at u211 or above. 
+
 ## Sub-task
 * [ZOOKEEPER-2168](https://issues.apache.org/jira/browse/ZOOKEEPER-2168) - Add C APIs for new createContainer Methods
 * [ZOOKEEPER-2481](https://issues.apache.org/jira/browse/ZOOKEEPER-2481) - Flaky Test: testZeroWeightQuorum