docs: correct image paths (#1535)

Co-authored-by: Anthony Fu <[email protected]>

docs/builtin/layouts.md

@@ -39,7 +39,7 @@ Shows an image on the left side of the screen, the content will be placed on the
 layout: image-left
 
 # the image source
-image: ./path/to/the/image
+image: /path/to/the/image
 
 # a custom class name to the content
 class: my-cool-content-on-the-right
@@ -57,7 +57,7 @@ Shows an image on the right side of the screen, the content will be placed on th
 layout: image-right
 
 # the image source
-image: ./path/to/the/image
+image: /path/to/the/image
 
 # a custom class name to the content
 class: my-cool-content-on-the-left
@@ -75,7 +75,7 @@ Shows an image as the main content of the page.
 layout: image
 
 # the image source
-image: ./path/to/the/image
+image: /path/to/the/image
 ---
 ```
 
@@ -84,15 +84,15 @@ You can change the default background size (`cover`) by adding the `backgroundSi
 ```yaml
 ---
 layout: image
-image: ./path/to/the/image
+image: /path/to/the/image
 backgroundSize: contain
 ---
 ```
 
 ```yaml
 ---
 layout: image-left
-image: ./path/to/the/image
+image: /path/to/the/image
 backgroundSize: 20em 70%
 ---
 ```