[IMP] doc: form view documentation improvement

Using studio odoo doesn't let user drop notebook in a group since it
generates issues with the notebook. (See https://github.com/odoo/enterprise/commit/ea5ccd548bb6781e5ccdf76cf11255c6fd6aa3cb

 )

For better understanding, a note for 'notebook' tag is added by this commit.

task -  2060330

closes odoo/odoo#41241

X-original-commit: a2d331af0df859fd29e84bfa30a9086c3d2e0fa8
Related: odoo/enterprise#7004
Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>