feat: resized blog images

README.md

@@ -91,6 +91,11 @@ __You would find the file `kermit.png` used on the `management` documentation pa
 
 * Global images (e.g: used in the footer) will be in the `img/theme/` subfolder.
 
+## Image sizes
+
+The ideal image plugin will generate reponsive images and placeholder for a faster page loading. 
+Since iamge can be quite heavy quite fast, the width of original images for blog post covers should be at 740px.
+
 ## License
 
 [![froggit.fr Copyright (c) 2021-present Lydra](https://cdn.icon-icons.com/icons2/2622/PNG/512/legal_license_mit_icon_157533.png)](https://choosealicense.com/licenses/mit/)