added link to haddock3 manual

Author: mgiulini

education/HADDOCK3/index.md

@@ -15,6 +15,9 @@ _Note that HADDOCK3 is still in heavy development and as such the software is ev
 * [**HADDOCK3 documentation**](https://www.bonvinlab.org/haddock3)
   Documentation for HADDOCK3 including [installation instructions](https://www.bonvinlab.org/haddock3/INSTALL.html){:target="_blank"}.
 
+* [**HADDOCK3 user manual**](https://www.bonvinlab.org/haddock3-user-manual/)
+  User manual for HADDOCK3, with a comprehensive description of the software and its features, including a [Best Practices](https://www.bonvinlab.org/haddock3-user-manual/bpg.html){:target="_blank"} section and descriptions of several [HADDOCK docking scenarios](https://www.bonvinlab.org/haddock3-user-manual/docking_scenarios.html){:target="_blank"}.
+
 * [**HADDOCK restraints generation**](https://www.bonvinlab.org/haddock-restraints/home.html){:target="_blank"}:
   A guide for the `haddock-restraints` tool allowing to generate various types of distance restraints for use in HADDOCK.