Highlight template for downlevel hosts

Signed-off-by: itowlson <ivan.towlson@fermyon.com>

Author: itowlson

content/v4/quickstart.md

@@ -231,7 +231,9 @@ You'll need the TinyGo compiler, as the standard Go compiler does not yet suppor
 {{card_element "template" "Zola SSG Template" "A template for using Zola framework to create a static webpage" "/hub/preview/template_zola_ssg" "rust" true }}
 {{blockEnd}}
 
-Now you are ready to create your first Spin application:
+Now you are ready to create your first Spin application.
+
+> The Rust, Go, and Python templates depend on Spin 4 and its support for WASI Preview 3. As Spin 4 is fairly new, some Spin hosts support only Spin 3.x. If you need to target such a host, look for a `http-<lang>-p2` template and use that instead.
 
 {{ tabs "sdk-type" }}
 

content/v4/writing-apps.md

@@ -258,6 +258,8 @@ HTTP path: /...
 
 All of these templates create a manifest containing a single component, and the source code for a minimal "hello world" component.
 
+> The Rust, Go, and Python templates depend on Spin 4 and its support for WASI Preview 3. As Spin 4 is fairly new, some Spin hosts support only Spin 3.x. If you need to target such a host, look for a `http-<lang>-p2` template and use that instead.
+
 ## Adding a New Component to an Application
 
 To add a new component to an existing application using a template, run the `spin add` command. This works in a very similar way to `spin new`, except that it expects the `spin.toml` file to already exist, and adds the details for the new component to that `spin.toml`.