Docs: move HA subsections to a deeper indentation level

Makes the table of contents read better

Author: Andrew Ash <andrew@andrewash.com>

Closes #2402 from ash211/docs/better-indentation and squashes the following commits:

ea0e130 [Andrew Ash] Move HA subsections to a deeper indentation level
[SPARK-3534] Fix expansion of testing arguments to sbt

Testing arguments to `sbt` need to be passed as an array, not a single, long string.

Fixes a bug introduced in #2420.

Author: Nicholas Chammas <nicholas.chammas@gmail.com>

Closes #2437 from nchammas/selective-testing and squashes the following commits:

a9f9c1c [Nicholas Chammas] fix printing of sbt test arguments
cf57cbf [Nicholas Chammas] fix sbt test arguments
e33b978 [Nicholas Chammas] Merge pull request #2 from apache/master
0b47ca4 [Nicholas Chammas] Merge branch 'master' of github.com:nchammas/spark
8051486 [Nicholas Chammas] Merge pull request #1 from apache/master
03180a4 [Nicholas Chammas] Merge branch 'master' of github.com:nchammas/spark
d4c5f43 [Nicholas Chammas] Merge pull request #6 from apache/master
[SPARK-3571] Spark standalone cluster mode doesn't work.

I think, this issue is caused by #1106

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2436 from sarutak/SPARK-3571 and squashes the following commits:

7a4deea [Kousuke Saruta] Modified Master.scala to use numWorkersVisited and numWorkersAlive instead of stopPos
4e51e35 [Kousuke Saruta] Modified Master to prevent from 0 divide
4817ecd [Kousuke Saruta] Brushed up previous change
71e84b6 [Kousuke Saruta] Modified Master to enable schedule normally
[SPARK-3564][WebUI] Display App ID on HistoryPage

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2424 from sarutak/display-appid-on-webui and squashes the following commits:

417fe90 [Kousuke Saruta] Added "App ID column" to HistoryPage
[SPARK-3567] appId field in SparkDeploySchedulerBackend should be volatile

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2428 from sarutak/appid-volatile-modification and squashes the following commits:

c7d890d [Kousuke Saruta] Added volatile modifier to appId field in SparkDeploySchedulerBackend
[SPARK-3565]Fix configuration item not consistent with document

https://issues.apache.org/jira/browse/SPARK-3565

"spark.ports.maxRetries" should be "spark.port.maxRetries". Make the configuration keys in document and code consistent.

Author: WangTaoTheTonic <barneystinson@aliyun.com>

Closes #2427 from WangTaoTheTonic/fixPortRetries and squashes the following commits:

c178813 [WangTaoTheTonic] Use blank lines trigger Jenkins
646f3fe [WangTaoTheTonic] also in SparkBuild.scala
3700dba [WangTaoTheTonic] Fix configuration item not consistent with document
[SPARK-3534] Add hive-thriftserver to SQL tests

Addresses the problem pointed out in [this comment](https://github.com/apache/spark/pull/2441#issuecomment-55990116).

Author: Nicholas Chammas <nicholas.chammas@gmail.com>

Closes #2442 from nchammas/patch-1 and squashes the following commits:

7e68b60 [Nicholas Chammas] [SPARK-3534] Add hive-thriftserver to SQL tests
[Minor] rat exclude dependency-reduced-pom.xml

Author: GuoQiang Li <witgo@qq.com>

Closes #2326 from witgo/rat-excludes and squashes the following commits:

860904e [GuoQiang Li] rat exclude dependency-reduced-pom.xml
[SPARK-3547]Using a special exit code instead of 1 to represent ClassNotFoundExcepti...

...on

As improvement of https://github.com/apache/spark/pull/1944, we should use more special exit code to represent ClassNotFoundException.

Author: WangTaoTheTonic <barneystinson@aliyun.com>

Closes #2421 from WangTaoTheTonic/classnotfoundExitCode and squashes the following commits:

645a22a [WangTaoTheTonic] Serveral typos to trigger Jenkins
d6ae559 [WangTaoTheTonic] use 101 instead
a2d6465 [WangTaoTheTonic] use 127 instead
fbb232f [WangTaoTheTonic] Using a special exit code instead of 1 to represent ClassNotFoundException
SPARK-3579 Jekyll doc generation is different across environments.

This patch makes some small changes to fix this problem:
1. We document specific versions of Jekyll/Kramdown to use that match
   those used when building the upstream docs.
2. We add a configuration for a property that for some reason varies across
   packages of Jekyll/Kramdown even with the same version.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #2443 from pwendell/jekyll and squashes the following commits:

54ee2ab [Patrick Wendell] SPARK-3579 Jekyll doc generation is different across environments.
[SPARK-3566] [BUILD] .gitignore and .rat-excludes should consider Windows cmd file and Emacs' backup files

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2426 from sarutak/emacs-metafiles-ignore and squashes the following commits:

a306020 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into emacs-metafiles-ignore
6a0a5eb [Kousuke Saruta] Added cmd file entry to .rat-excludes and .gitignore
897da63 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into emacs-metafiles-ignore
8cade06 [Kousuke Saruta] Modified .gitignore to ignore emacs lock file and backup file
[SPARK-3589][Minor]remove redundant code

https://issues.apache.org/jira/browse/SPARK-3589

"export CLASSPATH" in spark-class is redundant since same variable is exported before.
We could reuse defined value "isYarnCluster" in SparkSubmit.scala.

Author: WangTaoTheTonic <barneystinson@aliyun.com>

Closes #2445 from WangTaoTheTonic/removeRedundant and squashes the following commits:

6fb6872 [WangTaoTheTonic] remove redundant code
[SPARK-3560] Fixed setting spark.jars system property in yarn-cluster mode

Author: Victsm <victor.nju@gmail.com>
Author: Min Shen <mshen@linkedin.com>

Closes #2449 from Victsm/SPARK-3560 and squashes the following commits:

918405a [Victsm] Removed the additional space
4502a2a [Min Shen] [SPARK-3560] Fixed setting spark.jars system property in yarn-cluster mode.

(cherry picked from commit 832dff64ddb1240a4c8e22fcdc0e993cc8c808de)
Signed-off-by: Andrew Or <andrewor14@gmail.com>