Fix regression where external links are rendering as plaintext

[mportiz08]

Bug/issue #, if applicable: #885, 133444687

Summary

Fixes a regression introduced by #878 where external links are now rendering as plaintext strings instead of clickable links.

Resolves #885

Testing

Steps:

1. Checkout this branch and run the dev server with VUE_APP_DEV_SERVER_PROXY=https://jverkoey.github.io/slipstream npm run serve
2. Open http://localhost:8080/documentation/slipstream/slipstreamforswiftuidevelopers#Stacks and verify that the HStack and VStack strings are clickable links now (compare with main branch where they are plaintext)
3. Repeat testing instructions from Inactivate known external links #878 to ensure that functionality is not impacted by this change

Checklist

Make sure you check off the following items. If they cannot be completed, provide a reason.

• Added tests
• Ran npm test, and it succeeded
• Updated documentation if necessary

[mportiz08]

@swift-ci test

[jverkoey]

Thank you!

[mportiz08]

Thanks for catching this and bringing it to our attention @jverkoey!