fix: correct formatting and spacing in "Next Steps" section of quick-start.md

Author: Le-Caignec

src/overview/quick-start.md

@@ -91,11 +91,9 @@ learning and prototyping.
     buttonLabel="Open Sandbox"
     buttonIcon="mdi:code-braces"
     buttonHref="https://codesandbox.io/p/github/iExecBlockchainComputing/web3mail-sandbox/main"
-  />
-
-## Next Steps
+  /> </CardGrid>
 
-After exploring our starters and sandboxes:
+## Next StepsAfter exploring our starters and sandboxes
 
 1. **Choose Your Framework**: Start with our Next.js template or wait for
    React/Vue options