Bump roxygen2 version to 8.0.0

Change-Id: Ib5f5c66bd3db80d147370d2f16fc1c340240477c
diff --git a/man/RKorAPClient-package.Rd b/man/RKorAPClient-package.Rd
index ea38d7d..2ca335d 100644
--- a/man/RKorAPClient-package.Rd
+++ b/man/RKorAPClient-package.Rd
@@ -77,6 +77,11 @@
 \author{
 \strong{Maintainer}: Marc Kupietz \email{kupietz@ids-mannheim.de}
 
+Authors:
+\itemize{
+  \item Marc Kupietz \email{kupietz@ids-mannheim.de}
+}
+
 Other contributors:
 \itemize{
   \item Nils Diewald \email{diewald@ids-mannheim.de} [contributor]