[FW][IMP] iot: refactor and update configuration documentation

[fw-bot]

Restructure and update the IoT documentation.
(The doc pages in the Devices section will be updated in a separate PR)

Forward-Port-Of: #11518

[robodoo]

[fw-bot]

@auva-odoo cherrypicking of pull request #11518 failed.

stdout:

Auto-merging content/applications/finance/fiscal_localizations/belgium.rst
CONFLICT (modify/delete): content/applications/general/iot/config/troubleshooting.rst deleted in 831dfc8ded1dc49f8730a8b80a39358cdbffd9b8 and modified in 831c4a81df6ae0d30bb119ab997657b0c1273e8a.  Version 831c4a81df6ae0d30bb119ab997657b0c1273e8a of content/applications/general/iot/config/troubleshooting.rst left in tree.
CONFLICT (file location): content/applications/general/iot/config/troubleshooting/sub-type.png added in 831c4a81df6ae0d30bb119ab997657b0c1273e8a inside a directory that was renamed in 831dfc8ded1dc49f8730a8b80a39358cdbffd9b8, suggesting it should perhaps be moved to content/applications/general/iot/devices/printer/sub-type.png.
Auto-merging content/applications/sales/point_of_sale/configuration.rst
Auto-merging content/applications/sales/point_of_sale/shop/customer_display.rst
Auto-merging redirects/17.0.txt

Either perform the forward-port manually (and push to this branch, proceeding as usual) or close this PR (maybe?).

In the former case, you may want to edit this PR message as well.

⚠️ after resolving this conflict, you will need to merge it via @robodoo.

More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port

[auva-odoo]

@robodoo r+