orgcard.tex: Remove timeline reference

* doc/orgcard.tex: Don't mention timeline because this feature will be
  removed in version 9.1.

doc/orgcard.tex

@@ -571,7 +571,6 @@ after  ``{\tt :}'', and dictionary words elsewhere.
 \key{match tags, TODO kwds, properties}{C-c a m \noteone}
 \key{match only in TODO entries}{C-c a M \noteone}
 \key{find stuck projects}{C-c a \# \noteone}
-\key{show timeline of current org file}{C-c a L \noteone}
 \key{configure custom commands}{C-c a C \noteone}
 %\key{configure stuck projects}{C-c a ! \noteone}
 \key{agenda for date at cursor}{C-c C-o}