Added documentation for quality parameter

Added documentation for quality parameter for thumbnail()

content/docs/api/db/record/thumbnail/contents.lr

@@ -4,7 +4,7 @@ summary: Creates a thumbnail for an image.
 ---
 type: method
 ---
-signature: width, height=None, crop=False
+signature: width, height=None, crop=False, quality=None
 ---
 body:
 
@@ -17,6 +17,8 @@ given reactangle of width and height.  If height is not specified it will
 match the width and the height is set accordingly.  If cropping is enabled
 it's cropped around the edges to fit into the center.
 
+Quality parameter determines the compression of images where possible. If not passed the jpeg images get a default quality of 85 and png images get a default quality of 75.
+
 It provides the following attributes:
 
 * `width`: the thumbnail width in pixels.
@@ -34,3 +36,9 @@ to the exact dimensions provided instead of scaling it uncropped.
   <img src="{{ image.thumbnail(64)|url }}">
 {% endfor %}
 ```
+
+```html+jinja
+<img src="{{ image.thumbnail(1920, 1080, crop=True, quality=40)|url }}">
+```
+
+