Ensure docs projects have separate coding rules from src/test projects

Author: egil

docs/.editorconfig

@@ -1,3 +1,5 @@
+root = true
+
 [*]
 indent_style = space
 tab_size = 2

docs/Directory.Build.props

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+	<!-- Added here to prevent the Directory.Build.props from the src folder above to influence the docs projects. -->
+</Project>