Use main as branch for the "Edit on GitHub" link

Author: filiphr

config.toml

@@ -53,4 +53,4 @@ stableVersion = "1.5.5.Final"
 devVersion = "1.5.5.Final"
 numberOfLatestPosts = 7
 tagLine = "Java bean mappings, the easy way!"
-contentSourceUrl = "https://github.com/mapstruct/mapstruct.org/tree/master/content/"
+contentSourceUrl = "https://github.com/mapstruct/mapstruct.org/tree/main/content/"