docs: minor language clarification to try minimise confusion.

Author: sr55

source/docs/en/latest/workflow/adjust-quality.markdown

@@ -43,6 +43,8 @@ Recommended settings for **x264** and **x265** encoders:
 - RF 20-24 for 1080p Full High Definition[^1080p]
 - RF 22-28 for 2160p 4K Ultra High Definition[^2160p]
 
+These values may seem counter intuitive.  When using higher resolution source content, i.e. 4K, you have more data and quality to start with. Therefore, you can get away with using higher RF values than you can with lower resolution content as the loss is less perceptible.
+
 Raising quality minus 1-2 RF may produce better results when encoding animated `Sources` (anime, cartoons). Lower quality settings may be used to produce smaller files. Drastically lower settings may show significant loss of detail.
 
 Using higher than recommended quality settings can lead to *extremely large files* that may not be compatible with your devices. When in doubt, stick to the recommended range or use the default setting for the `Preset` you selected.