v4, alpha 6 (#17)

Reviewed-on: #17

src/Htmx/README.md

@@ -2,9 +2,11 @@
 
 This package enables server-side support for [htmx](https://htmx.org) within [Giraffe](https://giraffe.wiki) and ASP.NET's `HttpContext`.
 
-**htmx version: 2.0.8**
+**htmx version: 4.0.0-alpha6**
 
-_Upgrading from v1.x: the [migration guide](https://htmx.org/migration-guide-htmx-1/) does not currently specify any request or response header changes. This means that there are no required code changes in moving from v1.* to v2.*._
+_Upgrading from v2.x: the [migration guide](https://four.htmx.org/migration-guide-htmx-4/) lists changes for v4. For this package, the `HX-Trigger` and `HX-Trigger-Name` headers are marked obsolete. They are replaced by `HX-Source`, which provides the triggering tag name and `id` attribute. The `HX-Prompt` header has also been marked as obsolete, as the `hx-prompt` attribute which generated its content has been removed._
+
+_Obsolete elements will be removed in the first production v4 release._
 
 ### Setup
 
@@ -18,9 +20,9 @@ To obtain a request header, using the `IHeaderDictionary` extension properties:
 ```fsharp
 let myHandler : HttpHander =
     fun next ctx ->
-        match ctx.HxPrompt with
-        | Some prompt -> ... // do something with the text the user provided
-        | None -> ... // no text provided
+        match ctx.Target with
+        | Some elt -> ... // do something with id of the target element
+        | None -> ... // no target element provided
 ```
 
 To set a response header: