Update README.md

README.md

 #Installation
 From user side, we recommend the installation via pypi: 
-    $ pip install tfields
+    ```$ pip install tfields´´´
 
 
 #Testing:
 In the tfields directory, run
-    python tfields test
+    ```$ python tfields test´´´
 
 #Developers only:
 Clone this project with git
 To set up the shared git hooks, run
-    $ make init
+    ```$ make init´´´
 
 To check the coverage, we prefere the 'coverage' tool
 Use it in the tfields directory like so:
-    coverage run tfields test
+    ```coverage run tfields test´´´