diff 4.x and 5.x docs and sync some typos or description

[TianMing2018]

Please do not create a Pull Request without creating an issue first.

What is the purpose of the change

diff 4.x and 5.x docs and sync some typos or description

Brief changelog

diff 4.x and 5.x docs and sync some typos or description

Verifying this change

diff 4.x and 5.x docs and view those files

1. diff and corret some javascript to java in 05Exporter.md
2. diff and merge description of 02RocketMQEventBridgeOverview.md
3. diff and merge description of 02RocketMQMQTTQuickStart.md
4. diff and merge description of 01RocketMQ Connect Overview.md
5. diff and merge description of 02code-guidelines.md
6. diff and corret description of 04Dashboard.md

[TianMing2018]

By the way, here is three more problems I think we should viewed

1. the ports mentioned in 03Dashboard.md and 04Dashboard.md maybe outdated
2. the preview result was wired in 06message5.md cause :::note mark in section transaction message step，maybe we should move to the bottom of this section
3. should we diff 04release-manual.md and give a same manual?