Update Eclair manual building instructions

- Explain something that looks like a version number ("2.13").
- Explain how to skip tests, which are fragile on master and not run for the other clients.

node_client.asciidoc

@@ -886,7 +886,7 @@ $ mvn package
 [INFO] eclair-node-gui                                                    [jar]
 [INFO]
 [INFO] --------------------< fr.acinq.eclair:eclair_2.13 >---------------------
-[INFO] Building eclair_2.13 0.4.1-SNAPSHOT                                [1/4]
+[INFO] Building eclair_2.13 0.4.3-SNAPSHOT                                [1/4]
 [INFO] --------------------------------[ pom ]---------------------------------
 
 [...]
@@ -899,12 +899,16 @@ $ mvn package
 [INFO] BUILD SUCCESS
 [INFO] ------------------------------------------------------------------------
 [INFO] Total time:  01:06 min
-[INFO] Finished at: 2020-06-26T09:43:21-04:00
+[INFO] Finished at: 2020-12-12T09:43:21-04:00
 [INFO] ------------------------------------------------------------------------
 
 ----
 
-After several minutes the build of the Eclair package will complete. You will find the Eclair server node under +eclair-node/target+, packaged as a zip file. Unzip and run it, by following the instructions found here:
+The build logs above contain "2.13", for building a commit around version 0.4.3, this is expected.
+
+After several minutes the build of the Eclair package should complete. But the "package" action will also run tests, and some of them connect to the internet, which could fail. If you want to skip tests, add +-DskipTests+ to the command.
+
+Now, unzip and run the built package, by following the instructions found here:
 
 https://github.com/ACINQ/eclair#installing-eclair