Update the Java 11 doc as per review agreeement

doc/modules/cassandra/pages/new/java11.adoc

@@ -9,47 +9,34 @@ After Java 8 the next LTS version is Java 11. Java 9, 10, 12 and 13 are
 all non-LTS versions.
 
 One of the objectives of the Apache Cassandra 4.0 version is to support
-the recent LTS Java versions 8 and 11
+the LTS Java version 11
 (https://issues.apache.org/jira/browse/CASSANDRA-9608[CASSANDRA-9608]).
-Java 8 and Java 11 may be used to build and run Apache Cassandra 4.0. Effective Cassandra
+Java 11 may be used to build and run Apache Cassandra 4.0. Effective Cassandra
 4.0.2 there is full Java 11 support, it is not experimental anymore.
 
 == Support Matrix
 
-The support matrix for the Java versions for compiling and running
-Apache Cassandra 4.0 is detailed in Table 1. The build version is along
-the vertical axis and the run version is along the horizontal axis.
-
-Table 1 : Support Matrix for Java
-
-[width="68%",cols="34%,30%,36%",]
-|===
-| |Java 8 (Run) |Java 11 (Run)
-|Java 8 (Build) |Supported |Supported
-|Java 11(Build) |Not Supported |Experimental
-|===
-
 Apache 4.0 source code built with Java 11 cannot be run with
-Java 8.
+Java 8. We support it being run only on Java 11 at the moment.
 
-All binary releases are built with Java 8.
+All binary releases are built with Java 11.
 
-Next, we shall discuss using each of Java 8 and 11 to build and
+Next, we shall discuss using Java 11 to build and
 run Apache Cassandra 4.0.
 
-== Using Java 8 to Build
+== Using Java 11 to Build
 
-To start with, install Java 8. As an example, for installing Java 8 on
+To start with, install Java 11. As an example, for installing Java 11 on
 RedHat Linux the command is as follows:
 
 ....
-$ sudo yum install java-1.8.0-openjdk-devel
+$ sudo yum install java-11-openjdk
 ....
 
 Set the environment variables `JAVA_HOME` and `PATH`.
 
 ....
-$ export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk
+$ export JAVA_HOME=/usr/lib/jvm/java-11-openjdk
 $ export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
 ....
 
@@ -76,7 +63,7 @@ $ cd ~/cassandra
 $ ant
 ....
 
-Apache Cassandra 4.0 gets built with Java 8. Set the environment
+Apache Cassandra 4.0 gets built with Java 11. Set the environment
 variable for `CASSANDRA_HOME` in the bash script. Also add the
 `CASSANDRA_HOME/bin` to the `PATH` variable.
 
@@ -85,7 +72,7 @@ $ export CASSANDRA_HOME=~/cassandra
 $ export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin:$CASSANDRA_HOME/bin
 ....
 
-To run Apache Cassandra 4.0 with either of Java 8 or Java 11 run the
+To run Apache Cassandra 4.0 with Java 11 run the
 Cassandra application in the `CASSANDRA_HOME/bin` directory, which is in
 the `PATH` env variable.
 
@@ -129,56 +116,6 @@ INFO  [main] 2019-07-31 21:18:20,921 StorageService.java:2508 - Node 127.0.0.1:7
 jump to NORMAL
 ....
 
-== Using Java 11 to Build
-
-If Java 11 is used to build Apache Cassandra 4.0, first Java 11 must be
-installed and the environment variables set. As an example, to download
-and install Java 11 on RedHat Linux run the following command.
-
-....
-$ yum install java-11-openjdk-devel
-....
-
-Set the environment variables `JAVA_HOME` and `PATH`.
-
-....
-$ export JAVA_HOME=/usr/lib/jvm/java-11-openjdk
-$ export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
-....
-
-The build output should now include the following.
-
-....
-[echo] Non default JDK version used: 11
-...
-...
-_build_java:
-    [echo] Compiling for Java 11
-...
-...
-build:
-
-_main-jar:
-         [copy] Copying 1 file to /home/ec2-user/cassandra/build/classes/main/META-INF
-     [jar] Building jar: /home/ec2-user/cassandra/build/apache-cassandra-4.0-SNAPSHOT.jar
-...
-...
-_build-test:
-   [javac] Compiling 739 source files to /home/ec2-user/cassandra/build/test/classes
-    [copy] Copying 25 files to /home/ec2-user/cassandra/build/test/classes
-...
-...
-jar:
-   [mkdir] Created dir: /home/ec2-user/cassandra/build/classes/stress/META-INF
-   [mkdir] Created dir: /home/ec2-user/cassandra/build/tools/lib
-     [jar] Building jar: /home/ec2-user/cassandra/build/tools/lib/stress.jar
-   [mkdir] Created dir: /home/ec2-user/cassandra/build/classes/fqltool/META-INF
-     [jar] Building jar: /home/ec2-user/cassandra/build/tools/lib/fqltool.jar
-
-BUILD SUCCESSFUL
-Total time: 1 minute 3 seconds
-....
-
 == Common Issues
 
 The Java 11 built Apache Cassandra 4.0 source code may be run with Java