Use + instead of | to separate modifiers

Although | makes more logical sense, it has another meaning in most
shells.

 river/command/map.zig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/river/command/map.zig b/river/command/map.zig
index 90c0b33..3837a6f 100644
--- a/river/command/map.zig
+++ b/river/command/map.zig
@@ -62,7 +62,7 @@ pub fn map(
     };
 
     // Parse the modifiers
-    var it = std.mem.split(args[2], "|");
+    var it = std.mem.split(args[2], "+");
     var modifiers: u32 = 0;
     while (it.next()) |mod_name| {
         for (modifier_names) |def| {