doc/filters: fixes for scale filter

Adjusted formatting and prose for option force_divisible_by in scale filter

doc/filters.texi

@@ -15589,17 +15589,18 @@ Please note that this is a different thing than specifying -1 for @option{w}
 or @option{h}, you still need to specify the output resolution for this option
 to work.
 
-@item force_divisible_by Ensures that the output resolution is divisible by the
+@item force_divisible_by
+Ensures that both the output dimensions, width and height, are divisible by the
 given integer when used together with @option{force_original_aspect_ratio}. This
-works similar to using -n in the @option{w} and @option{h} options.
+works similar to using @code{-n} in the @option{w} and @option{h} options.
 
 This option respects the value set for @option{force_original_aspect_ratio},
-increasing or decreasing the resolution accordingly. This may slightly modify
-the video's aspect ration.
+increasing or decreasing the resolution accordingly. The video's aspect ratio
+may be slightly modified.
 
-This can be handy, for example, if you want to have a video fit within a defined
-resolution using the @option{force_original_aspect_ratio} option but have
-encoder restrictions when it comes to width or height.
+This option can be handy if you need to have a video fit within or exceed
+a defined resolution using @option{force_original_aspect_ratio} but also have
+encoder restrictions on width or height divisibility.
 
 @end table