Adding warning about long names
Adding warning about long names

Adding warning about long names into the Readme.md (See #9)
AzureADSamples/WebAPI-ManuallyValidateJwt-DotNet,AzureADSamples/WebAPI-ManuallyValidateJwt-DotNet,AzureADSamples/WebAPI-ManuallyValidateJwt-DotNet