externalize setup folder structure

docs/pages/bash/bash-0-setup.md

+### Setup
+
+
+First copy and paste this command to execute it. No worries not need to understand what it does.
+
+```bash
+course={{extra.working_directory}}
+mkdir -p ~/$course/script
+mkdir -p ~/$course/data
+echo "Welcome to the {{extra.working_directory}} course" > ~/$course/README
+echo "echo hello" >  ~/$course/script/script1.sh 
+echo "ATGC" >  ~/$course/data/data1.fa
+touch  ~/$course/data/dataA.fastq
+touch  ~/$course/data/dataB.fastq
+cd $course
+echo "done"
+```
+
+The command above prepare a {{extra.working_directory}} directory with material.

docs/pages/bash/bash-2-the-basics.md

@@ -71,6 +71,10 @@ Bash is often preferred over other shells for many reasons:
 
 ## The Unix directory structure 
 
+{%
+   include-markdown "pages/bash/bash-0-setup.md"
+%}
+
 **/ – The root directory**
 
 Everything, all the files and directories, in Linux are located under `root` represented by `/`. If you look at the directory structure, you’ll realize that it is similar to a plant’s root.

docs/pages/bash/bash-3-navigating.md

@@ -2,25 +2,11 @@
 
 Back to the directory structure... this time we will learn to `navigate between directories` and the difference between **absolute** and **relative** paths.
 
-## Prepare
+??? quote "First click and follow the instructions below only if you start the course at this stage! Otherwise skip this step!"
+    {%
+    include-markdown "pages/bash/bash-0-setup.md"
+    %}
 
-Back to the directory structure... this time we will learn difference between **absolute** and **relative** path and use a few commands in process.
-
-First copy and paste this command to execute it. No worries not need to understand what it does.
-
-```bash
-course={{extra.working_directory}}
-mkdir -p ~/$course/script
-mkdir -p ~/$course/data
-echo "Welcome to the {{extra.working_directory}} course" > ~/$course/README
-echo "echo hello" >  ~/$course/script/script1.sh 
-echo "ATGC" >  ~/$course/data/data1.fa
-touch  ~/$course/data/dataA.fastq
-touch  ~/$course/data/dataB.fastq
-echo "done"
-```
-
-The command above prepare a {{extra.working_directory}} directory with material.
 
 ## Where are we?
 
@@ -121,7 +107,7 @@ To move into a directory we have seen we can use the command `cd` and a director
 
 ## Relative path
 
-A `relative`` path is a path that specifies the location of a file or directory with respect to the current working directory. Any path that does not begin with a separator character ("/") is a relative path. 
+A `relative` path is a path that specifies the location of a file or directory with respect to the current working directory. Any path that does not begin with a separator character ("/") is a relative path. 
 
 !!! tip
     Relative path:  
@@ -190,12 +176,15 @@ We are now in the `script` directory.
     1. cd .
     2. cd ..
     3. cd ../..
-    4. cd /home/<userName>
+    4. cd /home/<userName\>
     5. cd ~
     6. cd home
     7. cd ~/data/..
     9. cd /
 
+??? example "Click to show the solution"
+    3,4,5
+
 ## File path Autocompletion
 
 It exist a wonderful behavior in Bash called the autocompletion. What it is? 

docs/pages/bash/bash-4-working_with_files_and_directories.md

 # Working with files and directories
 
-In theory you should be in the `script` directory.  
-Check using `pwd` and if it is not the case run `cd ~/{{extra.working_directory}}/script`
+??? quote "First click and follow the instructions below only if you start the course at this stage! Otherwise skip this step!"
+    {%
+    include-markdown "pages/bash/bash-0-setup.md"
+    %}
+
+Let's be sure to be in the `script` directory before to continue the rest of the training:
+```bash
+cd ~/{{extra.working_directory}}/script
+```
 
 ![](../images/3-navigation/tree_exo5.png){: style="height:250px"}