Change gradlew run command to bootRun

In contrast to :tomcatRun :bootRun works for me.

For :tomcatRun I was getting: Task 'tomcatRun' not found in project ':samples:boot'.

docs/src/docs/asciidoc/guides/boot.adoc

@@ -111,7 +111,7 @@ The boot Sample Application demonstrates how to use Spring Session to transparen
 
 You can run the sample by obtaining the {download-url}[source code] and invoking the following command:
 
-  $ ./gradlew :samples:boot:tomcatRun
+  $ ./gradlew :samples:boot:bootRun
 
 You should now be able to access the application at http://localhost:8080/
 
@@ -147,4 +147,4 @@ Alternatively, you can also delete the explicit key. Enter the following into yo
 
     $ redis-cli del spring:session:sessions:7e8383a4-082c-4ffe-a4bc-c40fd3363c5e
 
-Now visit the application at http://localhost:8080/ and observe that we are no longer authenticated.
+Now visit the application at http://localhost:8080/ and observe that we are no longer authenticated.