Update conf.py - adding sphinx_togglebutton extension
In order to be able to have collapsable admonitions for instance
````{admonition} #!/bin/bash - the shebang
:class: dropdown
The first line in this script also starts with a `#` followed by a `!`, and is not an ordinary comment.
This is a special the #!INTERPRETER character sequence and is called the shebang.
If a text file starts with it this interpreter is used instead of the default one. In our exmple we used `#!/bin/bash`.