[simple-scan] help: Use proper markup for Crop button, plus its actual tooltip text

[Andre Klapper <aklapper src gnome org>]

commit a332bf1646492fb0a261fa1e235a4558718096c9
Author: Andre Klapper <a9016009 gmx de>
Date:   Fri Feb 7 14:57:40 2020 +0100

    help: Use proper markup for Crop button, plus its actual tooltip text

 help/C/crop.page | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/help/C/crop.page b/help/C/crop.page
index 2ac8c6d..a4d6f45 100644
--- a/help/C/crop.page
+++ b/help/C/crop.page
@@ -37,7 +37,7 @@
 
     <steps>
       <title>Use the Toolbar</title>
-      <item><p>Click the "<gui>Crop</gui>" button in the toolbar.</p>
+      <item><p>Press the <gui style="button">Crop the selected page</gui> button in the toolbar.</p>
            <note style="tip"><p>This is the same as choosing "Custom" in step 2 of the
              aforementioned methods.</p></note></item>      
       <item><p>Click and hold the frame to move it to the desired position.</p></item>