Recommend source-build compatible dependabot pattern

Some .NET repos (e.g. [templating](https://github.com/dotnet/templating/blob/main/eng/dependabot/Packages.props) and [msbuild](https://github.com/dotnet/msbuild/blob/main/eng/dependabot/Packages.props)) have taken a dependency on utilizing dependabot to update dependencies. The standard pattern is not compatible w/source-build because the dependent package versions gets hard-coded and not overridable by source-build.

Investigation should be done to see if version properties can be utilized that source-build can override. Regardless on the finding repo follow-up needs to be done to update/recommend against the existing patterns being used. Source-build documentation should also be created that captures the recommendation.