add-template: add document for template fan

[giangvo]

Description:
Add document for template fans.

**Pull request in home-assistant

Checklist:

• Branch: Fixes, changes and adjustments should be created against current. New documentation for platforms/components and features should go to next.
• The documentation follow the standards.

[todschmidt]

Thanks for adding this. In the yaml file you don't need the '#' comments since that is defined in the configuration section. Also the example yaml at the top should contain only the most basic required settings You can provide a more detailed yaml file further down.

One question, how do the defaults of low,medium. high map to the 1,2,3 as you have it? It's just not clear how those are mapped in to me. Does 1 = low?

[giangvo]

@tschmidty69, speeds is for defining a list of available speeds which is used to validate return value of speed_template and also input value of set_speed. Values of speeds are also shown in speed select box on UI.

If you don't config speeds, its value is default to list of "low", "medium", "high" (It means speed_template should return "low", "medium" or "high" and you should see "low","medium","high" in the speed selection box in UI)

If you don't like the default value, you can set speeds to list of other values. e.g ["1","2","3"]
(It means speed_template should return "1", "2" or "3" and you should see "1","2","3" in the speed selection box in UI)

Hope that I explain it clear enough :). Feel free to ping me if you have more questions.
Cheer,

[frenck]

Rebased the PR in order to fix the build

[frenck]

Thanks, @giangvo! 🥇
Can be merged as soon as the parent PR gets merged.

[giangvo]

@frenck I created a new PR for this document: #5296
The main PR has been merged. Please review and merge it.
Thanks