chore: add AstroNvim v4 docs

Author: mehalter

netlify.toml

@@ -34,3 +34,9 @@ from = "/v3/*"
 to = "https://neon-salmiakki-8da50a.netlify.app/:splat"
 status = 200
 force = true                                            # COMMENT: ensure that we always redirect
+
+[[redirects]]
+from = "/v4/*"
+to = "https://harmonious-daifuku-19dac0.netlify.app/:splat"
+status = 200
+force = true                                                # COMMENT: ensure that we always redirect