Clean up extra quote in quagga "ospf distance global" help command

I noticed a minor typo today under [edit protocols ospf] when typing "set distance global" and hitting ? for help - it shows the help text literally as:
   <1-255>    Administrative distance"
...with the dangling quote on the end.
Traced it back here. I don't have a vyos build environment yet to confirm it, but it's a simple enough change anyway.
HTH!