Update CONTRIBUTING.md, ignore /omo - #45

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@v4, actions/setup-dotnet@v4, github/codeql-action/analyze@v3, github/codeql-action/init@v3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Because an application's API isn't typically referenced from outside the assembly, types can be made internal (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1515)

Avoid empty interfaces (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1040)

Because an application's API isn't typically referenced from outside the assembly, types can be made internal (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1515)

Avoid empty interfaces (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1040)