[IMP] sales: added important admonition to amazon docs

[ksc-odoo]

PROJECT TASK (request for adjustment): https://www.odoo.com/odoo/project.task/3983555?cids=3

Issue: Odoo limitation, can't sell the same product in FBA and FBM (will set 0 as the quantity)

Added IMPORTANT admonition blocks to the 2 Amazon Connector docs (in the Sales app section) that cover FBA and FBM concepts/topics. The admonition alerts the reader of the issue, and informs users that a correction to the issue should be happening in the near future.

This should be Forward-Ported through the latest version of 17...

[robodoo]

[ksc-odoo]

Alrighty, @larm-odoo -- this one is ready for a Peer Review (whenever you get a chance) -- it's just the addition of an admonition block in 2 different Amazon docs. The admonitions are the same, so this should be a quick review. Thanks! 👍

[ksc-odoo]

Alrighty, looks like this quick PR is ready for Final Review, @StraubCreative -- whenever you get a chance. Thanks! 👍

[ksc-odoo]

Thanks for the super-helpful feedback, @StraubCreative . I made that necessary adjustment, and believe this one is now ready for Tech Review, @samueljlieber (whenever you get a chance). Thanks! 👍

[ksc-odoo]

Thanks for the always-helpful feedback, @samueljlieber 👍

@robodoo r+