Prepare for release 6.6.0.3

Fix incorrect previous version in Readme.md

Add subscription supported script

Update the change log with release date for v6.5.0.3

Update release version in Readme.md and CHANGELOG.md

Merge pull request #154 from wso2/6.5.0

Merge 6.5.0 branch into Master branch

Add configuration readme

Merge pull request #104 from chirangaalwis/kubernetes-ei-fix-q2-merge…

…-conflicts

Merge 6.3.x branch to master branch

Merge pull request #96 from wso2/6.2.x

Merge 6.2.x branch to master branch

Merge pull request #87 from wso2/6.2.x

Merge 6.2.x branch to master branch