add python-pip as dep to build Manual

README.md

@@ -18,7 +18,7 @@ The documentation is powered by [Sphinx](http://www.sphinx-doc.org/en/stable/).
 Run the following command to install the needed dependencies:
 
 ```
-sudo apt install python3-sphinx texlive-full && pip install sphinx_bootstrap_theme
+sudo apt install python3-sphinx python-pip texlive-full && pip install sphinx_bootstrap_theme
 ```                                                                                                        
                                                                                                            
 You can see the options for building the documentation by running `make help`.