Update and examples on documentation on Card

[alinaradu]

The Card documentation is partially inaccurate. Here are a few remarks:

Types:

1. Text - typo

2. Image -- url: test for https -- provide example for server path

3. Card

   • Text - non documented - give example with mustache and say the root of the provided expression is always msg: {payload[0].SKU} = msg.payload[0].SKU

• Replace Subtitle with Subtext - mustache example. Root is always msg.
• Replace Attachement with Image
• Shared card - break line

4. Buttons properties: Show image - break lines. Example of URL Post-back - PB/IMB ? Dynamic buttons :
   • add how to "delete" the buttons - not clear enough. Card - include an image Carousel - include an image

[Klervix]

Hello @alinaradu, Feel free to make a pull request to update the documentation :)