Update presets-only mode docs

docs/configuration.md

@@ -111,7 +111,6 @@ There are two ways to define presets:
 ##### Using an environment variable
 
 * `IMGPROXY_PRESETS`: set of preset definitions, comma-divided. Example: `default=resizing_type:fill/enlarge:1,sharp=sharpen:0.7,blurry=blur:2`. Default: blank.
-* `IMGPROXY_ONLY_PRESETS`: disable all URL formats but presets. In this case, you always need to inform a valid preset. Example: `http://imgproxy.example.com/unsafe/thumbnail/plain/http://example.com/images/curiosity.jpg@png`
 
 ##### Using a command line argument
 
@@ -131,6 +130,12 @@ sharp=sharpen:0.7
 blurry=blur:2
 ```
 
+#### Using only presets
+
+imgproxy can be switched into "presets-only mode". In this mode, imgproxy accepts only `preset` option arguments as processing options. Example: `http://imgproxy.example.com/unsafe/thumbnail:blurry:watermarked/plain/http://example.com/images/curiosity.jpg@png`
+
+* `IMGPROXY_ONLY_PRESETS`: disable all URL formats and enable presets-only mode.
+
 ### Serving local files
 
 imgproxy can serve your local images, but this feature is disabled by default. To enable it, specify your local filesystem root:

docs/presets.md

@@ -24,8 +24,10 @@ A preset named `default` will be applied to each image. Useful in case you want
 
 ### Only presets
 
-If you set `IMGPROXY_ONLY_PRESETS` as `true`, a preset is obligatory, and all other URL formats are disabled.
+Setting `IMGPROXY_ONLY_PRESETS` as `true` switches imgproxy into "presets-only mode". In this mode imgproxy accepts presets list as processing options just like you'd specify them for the `preset` option:
 
-In this case, you always need to inform a preset in your URLs without the `preset` or `pr` statement. Example: `http://imgproxy.example.com/AfrOrF3gWeDA6VOlDG4TzxMv39O7MXnF4CXpKUwGqRM/thumbnail/aHR0cDovL2V4YW1w/bGUuY29tL2ltYWdl/cy9jdXJpb3NpdHku/anBn.png`
+```
+http://imgproxy.example.com/unsafe/thumbnail:blurry:watermarked/plain/http://example.com/images/curiosity.jpg@png
+```
 
-It's possible to use more than one preset separing them with `:` like `thumbnail:gray`.
+All othe URL formats are disabled in this mode.