doc: Update README.md file for current release

- maven version
- java version
- minor note to trace server command

Change-Id: Id46d103b8d76905527892dce19945053be597185
Signed-off-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/c/tracecompass.incubator/org.eclipse.tracecompass.incubator/+/206161
Tested-by: Trace Compass Bot <tracecompass-bot@eclipse.org>
Tested-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>

README.md

diff --git a/README.md b/README.md
index 98e186c..d46f1e2 100644
--- a/README.md
+++ b/README.md
@@ -38,9 +38,11 @@
 
 ## Compiling manually
 
-The Maven project build requires version 3.3 or later. It can be downloaded from
+The Maven project build requires version 3.9 or later. It can be downloaded from
 <http://maven.apache.org> or from the package management system of your distro.
 
+It also requires Java version 11 or later.
+
 To build the project manually using Maven, simply run the following command from
 the top-level directory:
 
@@ -116,7 +118,7 @@
 
     curl -X POST 'http://localhost:8080/tsp/api/traces' --header 'Content-Type: application/json' --data-raw '{ "parameters": { "uri": "/traces/kernel" } }'
 
-You can create an experiment with the kernel trace (or any opened trace) using the following command:
+You can create an experiment with the kernel trace (or any opened trace) using the command below. Replace the UUID with the UUID returned by the command above:
 
     curl -X POST 'http://localhost:8080/tsp/api/experiments' --header 'Content-Type: application/json' --data-raw '{ "parameters": { "name": "Experiment Name", "traces": ["d49d04f5-9db5-3773-ace4-1594b87db661"] } }'