Change tool version to 21.08.1 [skip ci]

[GaryShen2008]

Update the download link in docs

Signed-off-by: gashen gashen@nvidia.com

[GaryShen2008]

build

[NvTimLiu]

Local build PASS:

[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] RAPIDS Accelerator for Apache Spark Root Project 21.08.0-SNAPSHOT SUCCESS [  0.476 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin 21.08.0-SNAPSHOT SUCCESS [ 26.849 s]
[INFO] RAPIDS Accelerator for Apache Spark Shuffle Plugin 21.08.0-SNAPSHOT SUCCESS [  4.340 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Shims 21.08.0-SNAPSHOT SUCCESS [  0.059 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Spark 3.0.1 Shim 21.08.0-SNAPSHOT SUCCESS [  5.139 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Spark 3.0.1 EMR Shim 21.08.0-SNAPSHOT SUCCESS [  2.346 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Spark 3.0.2 Shim 21.08.0-SNAPSHOT SUCCESS [  2.361 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Spark 3.0.3 Shim 21.08.0-SNAPSHOT SUCCESS [  2.409 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Spark 3.1.1 Shim 21.08.0-SNAPSHOT SUCCESS [  9.104 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Spark 3.1.2 Shim 21.08.0-SNAPSHOT SUCCESS [  2.654 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Spark 3.1.1 Cloudera Shim 21.08.0-SNAPSHOT SUCCESS [  3.647 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Spark 3.0.4 Shim 21.08.0-SNAPSHOT SUCCESS [  1.868 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Spark 3.1.3 Shim 21.08.0-SNAPSHOT SUCCESS [  5.709 s]
[INFO] RAPIDS Accelerator for Apache Spark SQL Plugin Shim Aggregator 21.08.0-SNAPSHOT SUCCESS [  0.037 s]
[INFO] RAPIDS Accelerator for Apache Spark Scala UDF Plugin 21.08.0-SNAPSHOT SUCCESS [ 15.960 s]
[INFO] RAPIDS Accelerator for Apache Spark Distribution 21.08.0-SNAPSHOT SUCCESS [  6.369 s]
[INFO] rapids-4-spark-api-validation 21.08.0-SNAPSHOT ..... SUCCESS [  2.806 s]
[INFO] RAPIDS Accelerator for Apache Spark UDF Examples 21.08.0-SNAPSHOT SUCCESS [  2.597 s]
[INFO] RAPIDS Accelerator for Apache Spark Tests 21.08.0-SNAPSHOT SUCCESS [ 19.020 s]
[INFO] rapids-4-spark-integration-tests_2.12 21.08.0-SNAPSHOT SUCCESS [ 14.337 s]
[INFO] RAPIDS Accelerator for Apache Spark tools 21.08.1-SNAPSHOT SUCCESS [01:01 min]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  03:10 min
[INFO] Finished at: 2021-08-31T10:26:57+08:00
[INFO] ------------------------------------------------------------------------

[INFO] RAPIDS Accelerator for Apache Spark tools 21.08.1-SNAPSHOT SUCCESS [01:01 min]