docs: fix hugo warning: found no layout file for "html" for kind "term"

Hugo has been making this warning for a while

WARN found no layout file for "html" for kind "term": You should
create a template file which matches Hugo Layouts Lookup Rules for
this combination.

This turned out to be the addition of the `groups:` keyword to the
command frontmatter. Hugo is doing something with this keyword though
this isn't documented in the frontmatter documentation.

The fix was removing the `groups:` keyword from the frontmatter since
it was never used by hugo.

cmd/gendocs/gendocs.go

@@ -109,7 +109,13 @@ rclone.org website.`,
 				Title:       strings.ReplaceAll(base, "_", " "),
 				Description: commands[name].Short,
 				Source:      strings.ReplaceAll(strings.ReplaceAll(base, "rclone", "cmd"), "_", "/") + "/",
-				Annotations: commands[name].Annotations,
+				Annotations: map[string]string{},
+			}
+			// Filter out annotations that confuse hugo from the frontmatter
+			for k, v := range commands[name].Annotations {
+				if k != "groups" {
+					data.Annotations[k] = v
+				}
 			}
 			var buf bytes.Buffer
 			err := frontmatterTemplate.Execute(&buf, data)