[CLA] Add IBM CLA signature agreement

closes odoo/odoo#135679

Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>

doc/cla/corporate/ibm.md

+USA, 14 Sep 2023
+
+IBM agrees to the terms of the Odoo Corporate Contributor License
+Agreement v1.0.
+
+I declare that I am authorized and able to make this agreement and sign this
+declaration.
+
+Signed,
+
+Brad Topol btopol@us.ibm.com https://github.com/bradtopol
+
+List of contributors:
+
+Ludovic Gasc ludovic.gasc@be.ibm.com https://github.com/ludovic-gasc