fix(docs): broken link

[geromegrignon]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/scullyio/scully/blob/main/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Other... Please describe:

What is the current behavior?

On the doc app, there is no corresponding route for the DOCS link in the footer

What is the new behavior?

The route matchs the Introduction route.

Does this PR introduce a breaking change?

• Yes
• No

[geromegrignon]

@SanderElias for further contributions on the doc, do you want me to push the updated jest snapshot or you prefer to keep control on it?

[SanderElias]

@geromegrignon Feel free to push the updated snapshots. as long as its just docks snapshot that are changing.
We added this to the test suite because we now do an automated deploy, and we want to be sure the docs build.
Also, the docs use a different render path as our sample-blog and this makes sure both paths are working as expected.