Correct url link in citation (#3077)

JamesCuster · thomasp85 · commit 9a661d4c026e · 2019-01-19T17:54:58.000+01:00
diff --git a/inst/CITATION b/inst/CITATION
@@ -6,6 +6,6 @@ citEntry(entry = "book",
   publisher = "Springer-Verlag New York",
   year = "2016",
   isbn = "978-3-319-24277-4",
-  url = "http://ggplot2.org",
+  url = "https://ggplot2.tidyverse.org",
   textVersion = "H. Wickham. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York, 2016."
 )

Original file line number	Diff line number	Diff line change
`@@ -6,6 +6,6 @@ citEntry(entry = "book",`
`6`	`6`	`publisher = "Springer-Verlag New York",`
`7`	`7`	`year = "2016",`
`8`	`8`	`isbn = "978-3-319-24277-4",`
`9`		`- url = "http://ggplot2.org",`
	`9`	`+ url = "https://ggplot2.tidyverse.org",`
`10`	`10`	`textVersion = "H. Wickham. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York, 2016."`
`11`	`11`	`)`