picom.sample.conf: fix comment about focus-exclude

Closes #594

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

picom.sample.conf

@@ -116,7 +116,7 @@ inactive-opacity-override = false;
 # Dim inactive windows. (0.0 - 1.0, defaults to 0.0)
 # inactive-dim = 0.0
 
-# Specify a list of conditions of windows that should always be considered focused.
+# Specify a list of conditions of windows that should never be considered focused.
 # focus-exclude = []
 focus-exclude = [ "class_g = 'Cairo-clock'" ];