feat: only add description subject to table

[fty4]

Instead of adding the whole description to the table (inputs and outputs) only the first line should be added.

Similar to best practice of git commit messages the description would benefit if the description will be split to subject and body.
In the first line the basic information will be placed (subject).
Followed after a blank line the body will follow.

The full description (subject and body) will then be available in the usage section only.
This will improve the readability of the table.

Example

Usage

- uses: bitflight-devops/github-action-readme-generator@main
  with:
    # first line
    #
    # second after space
    # and another one
    #
    # Default: action.yml
    multiline-with-space: ""

    # first line
    # Default: action.yml
    singleline: ""

    # first line
    # but no space after ln
    # Default: action.yml
    multiline-without-space: ""

Inputs

Input	Description	Default	Required
multiline-with-space	first line	action.yml	false
singleline	first line	action.yml	false
multiline-without-space	first line but no space after ln	action.yml	false

Diff

Inputs

<!-- start inputs -->

| **Input**                                | **Description**                                              | **Default**             | **Required** |
| ---------------------------------------- | ------------------------------------------------------------ | ----------------------- | ------------ |
- | **<code>multiline-with-space</code>**   | first line<br /><br />second after space<br />and another one | <code>action.yml</code> | **false**    |
+ | **<code>multiline-with-space</code>**  | first line                                                    | <code>action.yml</code> | **false**    |
| **<code>singleline</code>**              | first line                                                    | <code>action.yml</code> | **false**    |
| **<code>multiline-without-space</code>** | first line<br />but no space after ln                         | <code>action.yml</code> | **false**    |

<!-- end inputs -->

[Jamie-BitFlight]

lgtm