[bugfix] Fix 301 status for a URL

Fixes:

Found the following (possibly) invalid URLs:
  URL: https://www.economist.com/blogs/graphicdetail (moved to https://www.economist.com/topics/graphic-detail)
    From: man/theme_economist.Rd
    Status: 301
    Message: Moved Permanently
For content that is 'Moved Permanently', please change http to https,
add trailing slashes, or replace the old by the new URL.

Author: jrnold

R/economist.R

@@ -135,7 +135,7 @@ scale_fill_economist <- function(...) {
 #'
 #' \code{theme_economist_white} implements a variant with a while
 #' panel and light gray (or white) background often used by \emph{The Economist}
-#' blog \href{https://www.economist.com/blogs/graphicdetail}{Graphic Detail}.
+#' blog \href{https://www.economist.com/topics/graphic-detail}{Graphic Detail}.
 #'
 #' Use \code{\link{scale_color_economist}()} with this theme.
 #' The x axis should be displayed on the right hand side.