fix typo in pricing.mdx

Author: seeekr

src/content/docs/workers-ai/platform/pricing.mdx

@@ -49,7 +49,7 @@ Pricing is based on input tokens.
 ## Image Generation
 Standard models are large image models such as `@cf/stabilityai/stable-diffusion-xl-base-1.0`
 Fast models are usually smaller image models that require fewer steps to generate an image, such as `@cf/black-forest-labs/flux-1-schnell` and `@cf/bytedance/stable-diffusion-xl-lightning`
-We take the maximum of the image height and width to calculate pricing. For example, and image of 1024x768 would fall under 1024x1024 pricing.
+We take the maximum of the image height and width to calculate pricing. For example, an image of 1024x768 would fall under 1024x1024 pricing.
 
 | Image Size   | Price                 |
 | ------------ | --------------------- |