Adding upstream version 0.8.9.

Signed-off-by: Daniel Baumann <daniel@debian.org>

docs/proxy.md

@@ -0,0 +1,21 @@
+To use a proxy with shoutrrr, you could either set the proxy URL in the environment variable `HTTP_PROXY` or override the default HTTP client like this:
+
+```go
+proxyurl, err := url.Parse("socks5://localhost:1337")
+if err != nil {
+	log.Fatalf("Error parsing proxy URL: %q", err)
+}
+
+http.DefaultClient.Transport = &http.Transport{
+	Proxy: http.ProxyURL(proxyurl),
+	DialContext: (&net.Dialer{
+		Timeout:   30 * time.Second,
+		KeepAlive: 30 * time.Second,
+	}).DialContext,
+	ForceAttemptHTTP2:     true,
+	MaxIdleConns:          100,
+	IdleConnTimeout:       90 * time.Second,
+	TLSHandshakeTimeout:   10 * time.Second,
+	ExpectContinueTimeout: 1 * time.Second,
+}
+```