Broken link in 3.3.13. CREATE UNIQUE

[codebling]

The link to MERGE seems to be broken in 3.3.13. CREATE UNIQUE

I'm not familiar enough with Asciidoc to figure out why it's not working, but the problem appears to lie in this file.

[jjaderberg]

@codebling We just published updates to the documentation which include a fix for the broken link. Thanks for reporting!