Update app links and images in README.md

[chepiok]

No description provided.

[sentry]

Bug: The README.md references resources/apps/Stokk.png, which is not present in the repository, resulting in a broken image link.
_{Severity: LOW}

Suggested Fix

Add the missing Stokk.png icon file to resources/apps/ as part of the PR, or update the image src to point to a valid accessible URL.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: README.md#L130

Potential issue: The newly added image reference in `README.md` points to
`https://raw.githubusercontent.com/techprimate/TPPDF/main/resources/apps/Stokk.png`, but
the image file `Stokk.png` is not included in the `resources/apps/` directory in the
repository. As a result, the image request will 404, causing the Stökk app icon to
render as broken in the "Apps using TPPDF" section.

_{Did we get this right? 👍 / 👎 to inform future reviews.}