feat: Added SecDim under Resources/Security

[lord-pendragon]

SecDim is an appsec edutainment platform with learning content based off real world examples and online appsec games, they have recently published learning content for Solidity as well as released a game for it on their play platform. Figured this might be relevant to solidity resources for security.

Checklist

• [x] The URL is not already present in the list (check with CTRL/CMD+F in the raw markdown file).
• [x] Each description starts with an uppercase character and ends with a period.
  Example: solc-js - JavaScript bindings for the compiler.
• [x] Drop all A / An prefixes at the start of the description.
• [x] Avoid using the word Solidity in the description.

[lord-pendragon]

Anyone? kindly respond

[lord-pendragon]

@bkrem need your review for this

[bkrem]

Thanks for adding 👍