Add media to Stonly guides

Choose from the below options to learn more: 

• Images: preferred option for step-by-step tutorials, mostly used to highlight an action 
• GIFs: preferred option for step-by-step tutorials, mostly used to show a set of actions 
• Pre-set icons: preferred option for linear or extended content, to illustrate an idea or a concept 
• Code: preferred option for technical documentation, compatible with all languages 
• None: preferred option for articles or specific Stonly content such as sequences or triggers