### _Why are the changes needed?_
- to consolidate styles in markdown files from manual written or auto-generated
- apply markdown formatting rules with flexmark from [spotless-maven-plugin](https://github.com/diffplug/spotless/tree/main/plugin-maven#markdown) to *.md files in `/docs`
- use `flexmark` to format markdown generation in `TestUtils` of common module used by `AllKyuubiConfiguration` and `KyuubiDefinedFunctionSuite`, as the same way in `FlexmarkFormatterFunc ` of `spotless-maven-plugin` using with `COMMONMARK` as `FORMATTER_EMULATION_PROFILE` (https://github.com/diffplug/spotless/blob/maven/2.30.0/lib/src/flexmark/java/com/diffplug/spotless/glue/markdown/FlexmarkFormatterFunc.java)
- using `flexmark` of` 0.62.2`, as the last version requiring Java 8+ (checked from pom file and bytecode version)
```
<markdown>
<includes>
<include>docs/**/*.md</include>
</includes>
<flexmark></flexmark>
</markdown>
```
- Changes applied to markdown doc files,
- no style change or breakings in built docs by `make html`
- removal all the first blank in licences and comments to conform markdown style rules
- tables regenerated by flexmark following as in [GitHub Flavored Markdown](https://help.github.com/articles/organizing-information-with-tables/) (https://github.com/vsch/flexmark-java/wiki/Extensions#tables)
### _How was this patch tested?_
- [x] regenerate docs using `make html` successfully and check all the markdown pages available
- [x] regenerate `settings.md` and `functions.md` by `AllKyuubiConfiguration` and `KyuubiDefinedFunctionSuite`, and pass the checks by both themselves and spotless check via `dev/reformat`
- [x] [Run test](https://kyuubi.readthedocs.io/en/master/develop_tools/testing.html#running-tests) locally before make a pull request
Closes#4200 from bowenliang123/markdown-formatting.
Closes#4200
1eeafce4 [liangbowen] revert minor changes in AllKyuubiConfiguration
4f892857 [liangbowen] use flexmark in markdown doc generation
8c978abd [liangbowen] changes on markdown files
a9190556 [liangbowen] apply markdown formatting rules with `spotless-maven-plugin` to markdown files with in `/docs`
Authored-by: liangbowen <liangbowen@gf.com.cn>
Signed-off-by: liangbowen <liangbowen@gf.com.cn>
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### _Why are the changes needed?_
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### _How was this patch tested?_
- [ ] Add some test cases that check the changes thoroughly including negative and positive cases if possible
- [x] Add screenshots for manual tests if appropriate
- [ ] [Run test](https://kyuubi.readthedocs.io/en/latest/develop_tools/testing.html#running-tests) locally before make a pull request
Closes#1557 from yaooqinn/ttk.
Closes#1557
8446180a [Kent Yao] [DOC] The TTL Of Kyuubi Engines
Authored-by: Kent Yao <yao@apache.org>
Signed-off-by: Kent Yao <yao@apache.org>
