update extension page

Author: fishjojo

source/user/extensions.md

@@ -24,14 +24,20 @@ MINDO3(mol).run()
 | --------------- | ------------------------------------------- |
 | cas_ac0         | https://github.com/CQCL/pyscf-ac0           |
 | cornell-shci    | https://github.com/pyscf/cornell-shci       |
+| ccpy            | https://github.com/piecuch-group/ccpy       |
+| cppe            | https://github.com/maxscheurer/cppe         |
 | dftd3           | https://github.com/pyscf/dftd3              |
+| dispersion      | https://github.com/pyscf/dispersion         |
 | dmrgscf         | https://github.com/pyscf/dmrgscf            |
 | doci            | https://github.com/pyscf/doci               |
 | fciqmc          | https://github.com/pyscf/fciqmc             |
+| forge           | https://github.com/pyscf/pyscf-forge        |
 | icmpspt         | https://github.com/pyscf/icmpspt            |
 | mbd             | https://github.com/pyscf/mbd                |
 | naive-hci       | https://github.com/pyscf/naive-hci          |
 | nao             | https://github.com/pyscf/nao                |
+| properties      | https://github.com/pyscf/properties         |
+| pyqmc           | https://github.com/WagnerGroup/pyqmc        |
 | qsdopt          | https://github.com/pyscf/qsdopt             |
 | rt              | https://github.com/pyscf/rt                 |
 | semiempirical   | https://github.com/pyscf/semiempirical      |