Put footnotes at the end of the doc

Author: JakeSCahill

modules/upgrade/pages/k-compatibility.adoc

@@ -53,21 +53,24 @@ Redpanda Core has no direct dependency on Kubernetes. Compatibility is influence
 |25.1.1-beta1, 0.4.41, 0.4.36
 |25.1.1-beta1, 2.4.x, 2.3.x
 |3.12+
-|1.28.x - 1.32.x{fn-k8s-compatibility}
+// d (default) here is required to get footnotes to appear at the bottom of the page
+// instead of inside the table cell.
+// See https://github.com/asciidoctor/asciidoctor/issues/2350#issuecomment-546841684
+d|1.28.x - 1.32.x{fn-k8s-compatibility}
 
 |24.3.x
 |25.1-k8s-beta, 5.9.x
 |25.1-k8s-beta, 0.4.41, 0.4.36, 0.4.29
 |25.1-k8s-beta, 2.4.x, 2.3.x, 2.2.x
 |3.11+
-|1.28.x - 1.31.x
+d|1.28.x - 1.31.x{fn-k8s-compatibility}
 
 |24.2.x
 |5.9.x, 5.8.x
 |0.4.29
 |2.2.x
 |3.10+
-|1.27.x - 1.30.x
+d|1.27.x - 1.30.x{fn-k8s-compatibility}
 |===
 
 By default, the Redpanda Helm chart depends on cert-manager for enabling TLS.