Change URL order in DESCRIPTION to be pkgdown-friendly (#2561)

Author: IndrajeetPatil

DESCRIPTION

@@ -18,7 +18,7 @@ Description: Checks adherence to a given style, syntax errors and possible
     'RStudio IDE', 'Emacs', 'Vim', 'Sublime Text', 'Atom' and 'Visual
     Studio Code'.
 License: MIT + file LICENSE
-URL: https://github.com/r-lib/lintr, https://lintr.r-lib.org
+URL: https://lintr.r-lib.org, https://github.com/r-lib/lintr
 BugReports: https://github.com/r-lib/lintr/issues
 Depends:
     R (>= 3.6)