Ignore Mermaid styling when purging CSS

Signed-off-by: Nic Cope <[email protected]>

Author: negz

themes/geekboot/assets/scss/docs.scss

@@ -50,4 +50,7 @@
 /* purgecss end ignore */
 @import "skippy";
 @import "fonts";
-@import "mermaid";
+// TODO(negz): Does import order matter? Can this go in the existing ignore block above?
+/* purgecss start ignore */
+@import "mermaid";
+/* purgecss end ignore */