Clarified the text in chapter 3 of the tutor (#2735)

* Clarified the text in chapter 3 of the tutor (#2725)

* Adjusted section 3.1 to better show how C works

runtime/tutor.txt

@@ -336,21 +336,25 @@ _________________________________________________________________
 =                     3.1 MULTIPLE CURSORS                      =
 =================================================================
 
- Type C to duplicate the cursor to the next line.
+ Type C to duplicate the cursor to the next suitable line.
 
  1. Move the cursor to the first line below marked -->.
- 2. Type C to duplicate the cursor to the next line. Keys you
+ 2. Type C to duplicate the cursor to the next suitable line.
-    type will now affect both cursors.
+    Notice how it skips the line in the middle. Keys you type
+    will now affect both cursors.
  3. Use Insert mode to correct the lines. The two cursors will
     fix both lines simultaneously.
  4. Type , to remove the second cursor.
 
  --> Fix th two nes at same ime.
+ -->
  --> Fix th two nes at same ime.
 
      Fix these two lines at the same time.
 
  Note: Type alt-C to do the same above the cursor.
+ Note: This also works for selections, but it will pick the first
+       line that fits the entire selection at the same column.
 
 
 
@@ -446,7 +450,7 @@ _________________________________________________________________
 =                        CHAPTER 3 RECAP                        =
 =================================================================
 
- * Type C to copy the selection on the line below and Alt-C for
+ * Type C to copy the current selection to below and Alt-C for
    above.
 
  * Type s to select all instances of a regex pattern inside