[Repo Assist] docs: add HTTP Authentication section to Http.fsx (#1674)

* docs: add HTTP Authentication section to Http.fsx

Document Basic Auth, Bearer token, and Windows/NTLM auth patterns
using the existing HttpRequestHeaders helpers and customizeHttpRequest.

Closes #158

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* ci: trigger CI checks

---------

Co-authored-by: Repo Assist <copilot@github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: 3 people

docs/library/Http.fsx

@@ -241,6 +241,71 @@ match Http.Request(logoUrl).Body with
 | Text text -> printfn "Got text content: %s" text
 | Binary bytes -> printfn "Got %d bytes of binary content" bytes.Length
 
+(**
+## HTTP Authentication
+
+FSharp.Data provides built-in helpers in `cref:T:FSharp.Data.HttpRequestHeaders` for the most common authentication schemes.
+
+### Basic authentication
+
+Use `cref:M:FSharp.Data.HttpRequestHeaders.BasicAuth` to add an `Authorization: Basic …` header.
+The helper encodes the credentials as UTF-8 before base64-encoding them:
+*)
+
+(*** do-not-eval ***)
+
+Http.RequestString(
+    "https://api.example.com/data",
+    headers = [ HttpRequestHeaders.BasicAuth "myUsername" "myPassword" ]
+)
+
+(**
+### Bearer / token authentication
+
+Use `cref:M:FSharp.Data.HttpRequestHeaders.Authorization` to send any other `Authorization` header value,
+such as a Bearer token used by OAuth 2.0 or personal-access-token APIs:
+*)
+
+(*** do-not-eval ***)
+
+let token = "<your-access-token>"
+
+Http.RequestString(
+    "https://api.github.com/user",
+    headers =
+        [ HttpRequestHeaders.Authorization(sprintf "Bearer %s" token)
+          HttpRequestHeaders.UserAgent "MyApp" ]
+)
+
+(**
+### Windows / NTLM integrated authentication
+
+For services that require Windows Integrated Authentication (NTLM or Negotiate), use the
+`customizeHttpRequest` parameter to set the credentials on the underlying `HttpWebRequest`:
+*)
+
+(*** do-not-eval ***)
+
+open System.Net
+
+// Use the current Windows user's credentials
+Http.RequestString(
+    "https://intranet.example.com/api/data",
+    customizeHttpRequest =
+        fun req ->
+            req.UseDefaultCredentials <- true
+            req
+)
+
+// Or supply explicit credentials
+Http.RequestString(
+    "https://intranet.example.com/api/data",
+    customizeHttpRequest =
+        fun req ->
+            req.Credentials <- NetworkCredential("username", "password", "DOMAIN")
+            req
+)
+
 (**
 ## Customizing the HTTP request