Add alternative install methods to readme

README.md

@@ -1,13 +1,13 @@
 # tmap: thematic maps in R
 
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@@ -59,9 +59,19 @@ The latest development version can be installed using `remotes`.
 In order to use the development version of `tmap`, it is recommended to use the development version of [tmaptools](https://github.com/r-tmap/tmaptools) as well:
 
 ```r
-library(remotes)
+# install.packages("remotes")
 install_github("r-tmap/tmaptools")
 install_github("r-tmap/tmap")
+
+# On Linux, with pak
+# install.packages("pak")
+pak::pak("r-tmap/tmap")
+
+# Or from r-universe
+options(repos = c(
+  janmarvin = 'https://r-tmao.r-universe.dev',
+  CRAN = 'https://cloud.r-project.org'))
+install.packages('tmap')
 ```
 
 See [NEWS](https://github.com/mtennekes/tmap/blob/master/NEWS) for the latest features and improvements and the [issue list](https://github.com/mtennekes/tmap/issues) for discussions of enhancements and bugs.