docs(windows): document required NuGet configuration (#3173)

docs/faq.md

@@ -0,0 +1,18 @@
+---
+title: Frequently Asked Questions
+---
+
+# error: could not find native static libraryWebView2LoaderStatic, perhaps an -L flag is missing?
+
+The WebView2 crate build pipeline requires `NuGet` to have a `PackageSource` to install the `Microsoft.Web.WebView2` package. If you never used `NuGet` before, you might need to create a file named `NuGet.Config` on `%APPDATA%/NuGet` folder, with the following contents:
+
+```
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <packageSources>
+    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
+  </packageSources>
+</configuration>
+```
+
+This configuration enables the default `NuGet` registry.