Add missing space

I've found a missing space between "or" and "CSF" of the paragraph "It will look for any stories available either in MDX or CSF and based on the documentation you've added it will display it..."

docs/writing-docs/build-documentation.md

@@ -28,7 +28,7 @@ At any point during your development, you can preview the documentation you've w
 
 Depending on your configuration, when you execute the `storybook-docs` script. Storybook will be put into documentation mode and will generate a different build.
 
-It will look for any stories available either in [MDX](./mdx.md) or[CSF](../writing-stories/introduction.md#component-story-format) and based on the documentation you've added it will display it...
+It will look for any stories available either in [MDX](./mdx.md) or [CSF](../writing-stories/introduction.md#component-story-format) and based on the documentation you've added it will display it...
 
 ![Storybook in documentation mode](./storybook-docs-build.png)