Fix for Warning on Check

an additional `:render` was wrongly placed and has been removed, travi build should work now and the build check worked on my end as well.
diff --git a/man/posterdown_latex.Rd b/man/posterdown_latex.Rd
index 3164ff5..8ae907c 100644
--- a/man/posterdown_latex.Rd
+++ b/man/posterdown_latex.Rd
@@ -16,7 +16,7 @@
 }
 \value{
 R Markdown output format to pass to
-\code{\link[rmarkdown:render:render]{rmarkdown:render::render()}}
+\code{\link[rmarkdown:render]{rmarkdown::render()}}
 }
 \description{
 Legacy function for the OG's of posterdown.