Fixed the syntax for a command in the 1.7.28 release notes.
Fixed the syntax for a command in the 1.7.28 release notes.

The command was showing as a broken link, since in ReST, surrounding
text with single backticks makes it a link. We now use :command:`...`
instead.

KnowNo/reviewboard,davidt/reviewboard,beol/reviewboard,KnowNo/reviewboard,beol/reviewboard,custode/reviewboard,sgallagher/reviewboard,sgallagher/reviewboard,reviewboard/reviewboard,bkochendorfer/reviewboard,davidt/reviewboard,custode/reviewboard,reviewboard/reviewboard,brennie/reviewboard,davidt/reviewboard,davidt/reviewboard,chipx86/reviewboard,KnowNo/reviewboard,brennie/reviewboard,brennie/reviewboard,brennie/reviewboard,custode/reviewboard,custode/reviewboard,beol/reviewboard,bkochendorfer/reviewboard,bkochendorfer/reviewboard,chipx86/reviewboard,reviewboard/reviewboard,KnowNo/reviewboard,chipx86/reviewboard,reviewboard/reviewboard,sgallagher/reviewboard,chipx86/reviewboard,beol/reviewboard,sgallagher/reviewboard,bkochendorfer/reviewboard