send to discord using embed - improve doc

[boly38]

Hi,

I like your project, thanks for this action.

I would like to improve embed doc:

• add a link to the discord official meaning of embed
• add some information about field limits (ex. description max length is 4096)
• add a sample of embed without using intermediate json file

example

      - name: Send my embed to discord channel
        uses: tsickert/discord-webhook@v4.0.0
        with:
          webhook-url: ${{ secrets.DISCORD_WEBHOOK_URL }}
          content: "this is embed sample"
          embed-title: "embed title"
          embed-description: "embed description"
          embed-thumbnail-url: "https://www.google.com/search?q=discord+embed"

I especially need a full working sample with embed-thumbnail-image and embed-thumbnail-url (on my side I dont see url nor image : bug?)

my original ideal is the following:

• with action-umami-report I have to send a given "report" to discord.
• If the report is small enough , then it can be sent using embed way.
• Else I can use "file upload" as fallback.
• I though it's possible using 2 conditionals steps using if expressions: step embed if report_length < 4096 // step upload file if report_length >= 4096