Add sanity check for funding / generator cmd for funding file

Signed-off-by: Knut Ahlers <knut@ahlers.me>

.config/sanity.d/has-funding.sh

@@ -0,0 +1,8 @@
+function sanity_has_funding() {
+	[[ -f .github/FUNDING.yml ]] || {
+		report warn "No FUNDING.yml config found"
+		return 0
+	}
+
+	report success "FUNDING.yml found"
+}

bin/ghfund

@@ -0,0 +1,11 @@
+#!/bin/bash
+set -euo pipefail
+
+mkdir -p .github
+cat -s >.github/FUNDING.yml <<EOF
+---
+
+github: [ Luzifer ]
+
+...
+EOF