doc/filters: fix order of tinterlace filter drop modes

Signed-off-by: Paul B Mahol <onemda@gmail.com>

doc/filters.texi

@@ -12669,8 +12669,8 @@ Output:
 22222                           44444
 @end example
 
-@item drop_odd, 1
-Only output even frames, odd frames are dropped, generating a frame with
+@item drop_even, 1
+Only output odd frames, even frames are dropped, generating a frame with
 unchanged height at half frame rate.
 
 @example
@@ -12684,14 +12684,14 @@ Frame 1         Frame 2         Frame 3         Frame 4
 11111           22222           33333           44444
 
 Output:
-                22222                           44444
-                22222                           44444
-                22222                           44444
-                22222                           44444
+11111                           33333
+11111                           33333
+11111                           33333
+11111                           33333
 @end example
 
-@item drop_even, 2
-Only output odd frames, even frames are dropped, generating a frame with
+@item drop_odd, 2
+Only output even frames, odd frames are dropped, generating a frame with
 unchanged height at half frame rate.
 
 @example
@@ -12705,10 +12705,10 @@ Frame 1         Frame 2         Frame 3         Frame 4
 11111           22222           33333           44444
 
 Output:
-11111                           33333
-11111                           33333
-11111                           33333
-11111                           33333
+                22222                           44444
+                22222                           44444
+                22222                           44444
+                22222                           44444
 @end example
 
 @item pad, 3
@@ -12805,9 +12805,11 @@ Output:
  11111   11111   22222   22222   33333   33333   44444
 @end example
 
+
 @item mergex2, 7
 Move odd frames into the upper field, even into the lower field,
 generating a double height frame at same frame rate.
+
 @example
  ------> time
 Input: