Clearify recommended vs no longer recommended adapters

[Hedda]

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Replaces https://github.com/zigpy/zigpy-znp/pull/146 and clarifies recommended versus older adapters no longer recommended for new purchase (for new users).

• Matches PR https://github.com/zigpy/zigpy-deconz/pull/251 (for zigpy-deconz), and https://github.com/zigpy/bellows/pull/614 (for bellows).

Note! Recommendations not accepted in ZHA docs unless info come from project -> https://github.com/home-assistant/home-assistant.io/pull/31839

Downstream project again want this information to be provided in upstream, see also https://github.com/home-assistant/home-assistant.io/pull/17089

Point is that older deconz adapter so not longer be seen as recommended for new purchase by those that are new to ZHA/zigpy.

If want older hardware/firmware to be seen as support but legacy then Home Assiatant devs want this to be stated upstream.