Merge pull request #185 from andyque/master

add 3.0 article
Merge pull request #186 from andyque/master

issue #3202, add a link to en catalog
update releaset note
Merge pull request #187 from minggo/doc-v3.0

update releaset note
Merge pull request #188 from andyque/master

issue #232, fix link error
Update en.md
Merge remote-tracking branch 'upstream/master'