[SPARK-3296][mllib] spark-example should be run-example in head notation of...

[SPARK-3296][mllib] spark-example should be run-example in head notation of DenseKMeans and SparseNaiveBayes

`./bin/spark-example`  should be `./bin/run-example` in DenseKMeans and SparseNaiveBayes

Author: wangfei <wangfei_hello@126.com>

Closes #2193 from scwf/run-example and squashes the following commits:

207eb3a [wangfei] spark-example should be run-example
27a8999 [wangfei] ./bin/spark-example should be ./bin/run-example

examples/src/main/scala/org/apache/spark/examples/mllib/DenseKMeans.scala

@@ -27,7 +27,7 @@ import org.apache.spark.mllib.linalg.Vectors
 /**
  * An example k-means app. Run with
  * {{{
- * ./bin/spark-example org.apache.spark.examples.mllib.DenseKMeans [options] <input>
+ * ./bin/run-example org.apache.spark.examples.mllib.DenseKMeans [options] <input>
  * }}}
  * If you use it as a template to create your own app, please use `spark-submit` to submit your app.
  */

examples/src/main/scala/org/apache/spark/examples/mllib/SparseNaiveBayes.scala

@@ -27,7 +27,7 @@ import org.apache.spark.mllib.util.MLUtils
 /**
  * An example naive Bayes app. Run with
  * {{{
- * ./bin/spark-example org.apache.spark.examples.mllib.SparseNaiveBayes [options] <input>
+ * ./bin/run-example org.apache.spark.examples.mllib.SparseNaiveBayes [options] <input>
  * }}}
  * If you use it as a template to create your own app, please use `spark-submit` to submit your app.
  */