Add blog to docs (#484)

* Adding social card infrastructure
* Upgrades doc project to .NET 6
* Adds Playwright
* Changes the console to a web project for Playwright
* Adds social card template
* Added blog content
* Parallelized social image processing
* Updating CI to use .NET 6 for docs build

docs/global.json

@@ -0,0 +1,6 @@
+{
+  "sdk": {
+    "version": "2.2.200",
+    "rollForward": "latestMajor"
+  }
+}