docs: update  v2.4 faq

增加了六个社区常见问题及其回答。

Update 08-taos-shell.md

docs:cdiwadkar16-patch-4-36 - rephrasing

docs:cdiwadkar16-patch-4-35 - minor

Rephrased sentences.

docs:cdiwadkar16-patch-4-34 - minor

docs:cdiwadkar16-patch-4-33 - minor changes

Rephrasing in some places.

Minor stylistic changes.

Additions, rephrasing.

docs:cdiwadkar16-patch-4-32 - several

Some additions, stylistic changes, grammar, spelling changes.

docs:cdiwadkar16-patch-4-31 - few changes

Added some phrases.
Stylistic changes.

docs:cdiwadkar16-patch-4-30 - minor

docs:cdiwadkar16-patch-4-29 - minor

docs:cdiwadkar16-patch-4-28 - minor changes

docs:cdiwadkar16-patch-4-27 - several

stylistic change

grammatical, stylistic and one spelling change.

docs:cdiwadkar16-patch-4-26 - several

Minor changes - grammatical, stylistic

grammatical, stylistic and added tumbling window to concept of "flip time" window.

Grammatical, stylistic and other changes.

docs:cdiwadkar16-patch-4-25 - several changes

grammatical and stylistic changes.

copy docs-exmple-test to branch 2.4

docs:cdiwadkar16-patch-4-24 - minor changes

Rephrased a sentence and 2 phrases

docs: formatting errors: tdinsight

docs: broken link: Kafka

docs: phrasing: EMQX broker

docs: typos: grafana

docs: change city names in docs-examples