Re-licence to MIT (#306)

* Re-licence to MIT

cf. #305

also, see easystats/easystats#368

* fix typo

* fix R CMD check issue

.Rbuildignore

@@ -5,7 +5,6 @@
 ^\_pkgdown.yml
 ^\_pkgdown.yaml
 
-^LICENSE
 ^logo.png
 ^README.Rmd
 ^README.md
@@ -29,3 +28,4 @@
 ^cran-comments\.md$
 ^revdep$
 ^CRAN-SUBMISSION$
+^LICENSE\.md$

DESCRIPTION

@@ -54,7 +54,7 @@ Description: Provides plotting utilities supporting packages in the 'easystats'
     geoms, and scales for 'ggplot2'. Color scales are based on
     <https://materialui.co/colors>. 
     References: Lüdecke et al. (2021) <doi:10.21105/joss.03393>.
-License: GPL-3
+License: MIT + file LICENSE
 URL: https://easystats.github.io/see/
 BugReports: https://github.com/easystats/see/issues
 Depends: