add link to anitbody-antigen Sofia video (#725)

* add link to anitbody-antigen Sofia video

* embed video

Author: AnnaKravchenko

education/HADDOCK3/HADDOCK3-antibody-antigen/index.md

@@ -11,7 +11,6 @@ This tutorial consists of the following sections:
 * table of contents
 {:toc}
 
-<hr>
 <hr>
 
 ## Introduction
@@ -20,6 +19,10 @@ This tutorial demonstrates the use of the new modular HADDOCK3 version for predi
 the structure of an antibody-antigen complex using knowledge of the hypervariable loops
 on the antibody (i.e., the most basic knowledge) and epitope information identified from NMR experiments for the antigen to guide the docking.
 
+This tutorial was recorded at the BioExcel Sofia Workshop in May 2025:
+<iframe width="560" height="315" src="https://www.youtube.com/embed/0pLOPev3ni0?si=RaI2lT7iX9USleZo" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
+
+<br>
 An antibody is a large protein that generally works by attaching itself to an antigen,
 which is a unique site of the pathogen. The binding harnesses the immune system to directly
 attack and destroy the pathogen. Antibodies can be highly specific while showing low immunogenicity (i.e. the ability to provoke an immune response),

education/HADDOCK3/index.md

@@ -35,7 +35,7 @@ _Note that HADDOCK3 is still in heavy development and as such the software is ev
   </ul>
 
 * [**Basic docking run with HADDOCK3**](/education/HADDOCK3/HADDOCK3-antibody-antigen):
-  This tutorial describes a full step-by-step process from preparing the files for the docking, to the interpretation of the results. It is a good idea to go through it to get a basic introduction to HADDOCK3. *Note that this is the basic antibody-antigen tutorial; if you've already followed it elsewhere, there's no need to repeat it.*
+  This tutorial describes a full step-by-step process from preparing the files for the docking, to the interpretation of the results. The tutorial is available as a video [**here**](https://youtu.be/0pLOPev3ni0?feature=shared){:target="_blank"}. It is a good idea to go through it to get a basic introduction to HADDOCK3. *Note that this is the basic antibody-antigen tutorial; if you've already followed it elsewhere, there's no need to repeat it.*
 
 <hr>