Improve visibility of the docs and license (#109)

* add badge for the docs

* change style of the badge

* change style of the badge

* add a explicit link to docs in the README file

* add badge with the license

* fix link to license

* make the banner of docs blue

README.md

@@ -8,10 +8,14 @@
 
 ![GitHub Actions](https://github.com/pyMBE-dev/pyMBE/actions/workflows/testsuite.yml/badge.svg)
 [![codecov](https://codecov.io/gh/pyMBE-dev/pyMBE/branch/main/graph/badge.svg)](https://codecov.io/gh/pyMBE-dev/pyMBE)
+[![docs](https://badgen.net/static/docs/up-to-date/blue/)](pymbe-dev.github.io/pyMBE/pyMBE.html) 
+[![License: GPL v3](https://img.shields.io/badge/License-GPLv3-blue.svg)](LICENSE.txt)
 [![Contributor Covenant](https://img.shields.io/badge/Contributor%20Covenant-2.1-4baaaa.svg)](CODE_OF_CONDUCT.md) 
 
 pyMBE provides tools to facilitate building up molecules with complex architectures in the Molecular Dynamics software [ESPResSo](https://espressomd.org/wordpress/). Some examples of molecules that can be set up with pyMBE are polyelectrolytes, peptides and proteins. pyMBE bookkeeps all the information about the molecule topology, permitting to link each particle to its corresponding residue and molecule. pyMBE uses the [Pint](https://pint.readthedocs.io/en/stable/) library to enable input parameters in any arbitrary unit system, which is later transformed in the reduced unit system used in ESPResSo.
 
+An up-to-date documentation of all methods of the library can be found [here](pymbe-dev.github.io/pyMBE/pyMBE.html) and in the source code.
+
 ## Dependencies
 
 - [ESPResSo](https://espressomd.org/wordpress/)