setup: fix virtual environment

Uses production version of `reana-client` that is now sufficient.

Uses production virtual environment on LXPLUS instead of personal one.

Adds `reana-client` testing after installation.

Fixes shell command and output markup.

_episodes/02-first-example.md

@@ -214,12 +214,9 @@ Options:
 The REANA client will interact with a remote REANA cluster. It knows to which REANA cluster it connects by means of the following environment variable:
 
 ```bash
-$ source /afs/cern.ch/user/r/reana/public/bin/reana/activate/
 $ export REANA_SERVER_URL=https://reana.cern.ch
 ```
 
-The source command is for lxplus users only.
-
 In order to authenticate to REANA, you need to generate a token.
 
 > ## Exercise: Obtain a token.

setup.md

@@ -10,21 +10,33 @@ This lesson teaches the principles of containerised scientific workflows by mean
 The participants should either install [reana-client](https://pypi.org/project/reana-client/) on
 their laptops:
 
+~~~bash
+virtualenv ~/.virtualenvs/reana
+source ~/.virtualenvs/reana/bin/activate
+pip install reana-client
 ~~~
-$ virtualenv ~/.virtualenvs/reana
-$ source ~/.virtualenvs/reana/bin/activate
-$ pip install --pre reana-client
+{: .source}
+
+Alternatively, the participants can log into CERN's LXPLUS cluster using `ssh lxplus.cern.ch` and
+activate a pre-existing environment there:
+
+~~~bash
+source /afs/cern.ch/user/r/reana/public/reana/bin/activate
 ~~~
-{: .bash}
+{: .source}
 
-Alternatively, the participants can log into CERN's LXPLUS cluster and use a pre-existing
-environment there:
+After installation of `reana-client`, please check whether the client works by asking for its
+version:
+
+~~~bash
+reana-client version
+~~~
+{: .source}
 
 ~~~
-$ ssh lxplus.cern.ch
-lxplus> source ~simko/public/reana/bin/activate
+0.9.1
 ~~~
-{: .bash}
+{: .output}
 
 ---