Fix Java SimpleApp spark application

## What changes were proposed in this pull request?

Add missing import and missing parentheses to invoke `SparkSession::text()`.

## How was this patch tested?

Built and the code for this application, ran jekyll locally per docs/README.md.

Author: Christiam Camacho <camacho@ncbi.nlm.nih.gov>

Closes #18795 from christiam/master.

docs/quick-start.md

@@ -297,12 +297,13 @@ We'll create a very simple Spark application, `SimpleApp.java`:
 {% highlight java %}
 /* SimpleApp.java */
 import org.apache.spark.sql.SparkSession;
+import org.apache.spark.sql.Dataset;
 
 public class SimpleApp {
   public static void main(String[] args) {
     String logFile = "YOUR_SPARK_HOME/README.md"; // Should be some file on your system
     SparkSession spark = SparkSession.builder().appName("Simple Application").getOrCreate();
-    Dataset<String> logData = spark.read.textFile(logFile).cache();
+    Dataset<String> logData = spark.read().textFile(logFile).cache();
 
     long numAs = logData.filter(s -> s.contains("a")).count();
     long numBs = logData.filter(s -> s.contains("b")).count();

docs/structured-streaming-programming-guide.md

@@ -1041,8 +1041,8 @@ streamingDf.join(staticDf, "type", "right_join")  // right outer join with a sta
 <div data-lang="java"  markdown="1">
 
 {% highlight java %}
-Dataset<Row> staticDf = spark.read. ...;
-Dataset<Row> streamingDf = spark.readStream. ...;
+Dataset<Row> staticDf = spark.read(). ...;
+Dataset<Row> streamingDf = spark.readStream(). ...;
 streamingDf.join(staticDf, "type");         // inner equi-join with a static DF
 streamingDf.join(staticDf, "type", "right_join");  // right outer join with a static DF
 {% endhighlight %}
@@ -1087,7 +1087,7 @@ streamingDf
 <div data-lang="java"  markdown="1">
 
 {% highlight java %}
-Dataset<Row> streamingDf = spark.readStream. ...;  // columns: guid, eventTime, ...
+Dataset<Row> streamingDf = spark.readStream(). ...;  // columns: guid, eventTime, ...
 
 // Without watermark using guid column
 streamingDf.dropDuplicates("guid");