added plugin YOURLS-Custom-Header name

[srivastava07]

This plugin enables the addition of a custom header to the URL, facilitating compliance with regulatory requirements in certain countries, such as India, for bulk SMS services. Pass custom_header in query param to add custom header as prefix to the generated short url

[LeoColomb]

Thanks for submitting this pull request, @srivastava07.
Let's make the name a bit more readable.
Also, don't hesitate to add a license file to your project to ease its use and open it for contributions. https://github.com/srivastava07/YOURLS-Custom-Header/community/license/new?branch=main

[srivastava07]

@LeoColomb I have added the LICENSE file, Thanks for the suggestion.

[dgw]

I don't understand how this prefix counts as a "header", but the addition here looks fine assuming that users who know (and need) what this does will recognize it in the list.