Update baseline version and add release process doc (#1199)

Author: twsouthwick

RELEASE.md

@@ -0,0 +1,7 @@
+# Release Process
+
+1. Update CHANGELOG.md with user visible changes
+2. Ensure backend is building successfully (it verifies that all data we expect is present in the SDK)
+3. Create release (tag)
+4. Create AzDo Release to push to NuGet.org
+5. Update `PackageValidationBaselineVersion` [here](src/Directory.Build.targets) to new version for backwards compatibility checks

src/Directory.Build.targets

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <EnablePackageValidation>true</EnablePackageValidation>
-    <PackageValidationBaselineVersion>2.16.0</PackageValidationBaselineVersion>
+    <PackageValidationBaselineVersion>2.17.1</PackageValidationBaselineVersion>
   </PropertyGroup>
 
   <Import Project="..\Directory.Build.targets" />