feat: added Gotenberg, a Docker-powered stateless API for PDF files

[nktnet1]

Thanks for taking the time to suggest an addition to awesome-selfhosted!

To ensure your Pull Request is dealt with swiftly, please check the following (check the boxes [x]):

• Submit one item per pull request. This eases reviewing and speeds up inclusion.
• You have searched the repository for any relevant issues or PRs, including closed ones.
• Any software you are adding is not already listed at any of awesome-sysadmin, staticgen.com, staticsitegenerators.net, dbdb.io.
• The file you are adding is formatted as described in addition.md.
• Demo links should only be used for interactive demos, i.e. not video demonstrations.
• Comments and unused optional fields have been removed.
• The file you are adding uses kebab-case file naming, for example my-awesome-software.yml.
• Values for platform are the main server-side requirements for the software. Don't include frameworks or specific dialects.
• Any software project you are adding to the list is actively maintained.
• Any software project you are adding was first released more than 4 months ago.
• Any software project you are adding has working installation instructions.
• You understand that your Pull Request will be merged ~1 week after approval, to allow for further comments if needed.

[Rabenherz112]

We only list end-user applications, as far as I see Gotenberg doesn't have a direct way for end-users to interact with it (such as a webui), but instead solely relies on their API.

[nktnet1]

We only list end-user applications, as far as I see Gotenberg doesn't have a direct way for end-users to interact with it (such as a webui), but instead solely relies on their API.

I see... thank you for the review and clarification @Rabenherz112.

This wasn't obvious to me from the descriptions on the original awesome-selfhosted repository:

I thought Gotenberg would've at the least fallen under the Network Service category that was linked.

I also noticed similar Server/API-based/CLI projects (added a few more just now) such as

• textbelt
• ydl_api_ng
• supysonic
• libretranslate
• vaultwarden

so I thought it would've been okay to add Gotenberg.
However, I've only skimmed over these, so perhaps they satisfied the WebUI requirement in some other way (e.g. vaultwarden I supposed can be paired with the Bitwarden frontend?)

Would you like me to close this pull request?

[Ki-er]

Slightly cleaner description

[nodiscc]

Disregard the linter error, unrelated

[nktnet1]

I've merged the main branch into this one, which did remove the unrelared lint issue ^_^.