During my research about adding the .resx files to all the projects for each language noticed that also we need to have the fallback_docs folder for each language.
Then in this PR I'm proposing a change in the DynamoCore.csproj file for copying the md files to the fallback_docs inside each language folder, not sure if this change is needed due that we need to be sure that localization team has the changes for translating the md files once they are in this new location.

moving md files to the en-US folder and updating the DynamoCore.csproj for copying the files from the new location.

Fix that will be copying all the md files inside each language folder like Dynamo\doc\distrib\NodeHelpFiles\en-US to the output path: Dynamo\bin\AnyCPU\Debug\en-US\fallback_docs

I've updated the csproj file for using only one entry for copying the SAT and TXT files from en-US folder to each folder language.