feat(set_cubes_cw_max_version): add custom MR description

cube_doctor/transforms/set_cubes_cw_max_version.py

@@ -27,6 +27,13 @@ class SetCubeCubicWebMaxVersion(Command):
     AUTO_MR_AUTO_MERGE = True
     TARGETS = ("cubes",)
 
+    merge_request_description = (
+        "Hello dear contributors,\n\nThis is an auto generated MR to set a higher born for the "
+        "cubicweb dependency and automatically increase it on release if the test pass. You can "
+        "find more information here: "
+        "https://forge.extranet.logilab.fr/cubicweb/cubicweb/-/issues/387"
+        "\n\nKind regards,"
+    )
 
     base_query = "?project lgg:has_py3_tests true ."