Fix rustdoc formatting issue.
Fix rustdoc formatting issue.

dherman/nanny,neon-bindings/neon,rustbridge/neon,rustbridge/neon,dherman/nanny,neon-bindings/neon,rustbridge/neon,dherman/nanny,neon-bindings/neon,dherman/nanny,neon-bindings/neon,rustbridge/neon,rustbridge/neon,rustbridge/neon