[Feature-339][admin,web] Add alarmMsg sending test

[Optimization-3443][doc] Add sidebar dinky logo

Modify the document file to lower case

[Document-336][doc] Modify document

[Optimization-334][doc, alert] Optimizati关于 doc 在dex && Optimization Misspelled words 

[Document-332][docs] Add flinksql Development Guide

[Optimize-330][docs]  Optimize official documents 

[Fix-328][docs]Modify the Chinese and English navigation bar and sidebar

[Document-326][doc] Modify introduction and concept and feature

[Document-324][doc]update registerCenter relevant

[Feature-309][alert] Add Email Alert Type

[Fix-310][gateway]Configure hadoop_conf for Flink

[fix-239][core] Use "==" to judge whether the values of referenced variables are equal. Replace with the equals function.

[fix-239][core] Use "==" to judge whether the values of referenced variables are equal. Replace with the equals function.

[fix-239][core] Use "==" to judge whether the values of referenced variables are equal. Replace with the equals function.