docs: change to german name

Author: m-muecke

DESCRIPTION

@@ -2,7 +2,7 @@ Package: treasury
 Title: Client for US Treasury XML Feed and Published Data
 Version: 0.2.0.9000
 Authors@R:
-    person("Maximilian", "Muecke", , "[email protected]", role = c("aut", "cre"),
+    person("Maximilian", "Mücke", , "[email protected]", role = c("aut", "cre"),
            comment = c(ORCID = "0009-0000-9432-9795"))
 Description: Download daily interest rates from the US Treasury XML feed.
     Leveraging