Outdated install info on readme

[adrianinsaval]

The readme file still states that assembly3 cannot work in regular freecad, which is no longer true as it is even bundled in the conda builds. Could you update the readme file to reflect this and give proper install instructions? git clone into the mod directory is apparently not enough as the solver is not included and it's not obvious to me (and possibly many others) how and where it should be installed. Thanks for all your great work!

[adrianinsaval]

Link to a post by a confused user where I couldn't give proper help because I don't know how to install the solver: https://forum.freecadweb.org/viewtopic.php?f=20&t=57224

[adrianinsaval]

Thanks!