Fix typo in init files.

lib/init/src/root.zig

@@ -1,6 +1,6 @@
 //! By convention, root.zig is the root source file when making a library. If
 //! you are making an executable, the convention is to delete this file and
-//! start with root.zig instead.
+//! start with main.zig instead.
 const std = @import("std");
 const testing = std.testing;