docs/faq: update relative links

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

docs/faq/product.md

@@ -46,7 +46,7 @@ source candidates. (And we'll probably end up writing some brand new ones, too.)
 ### What's the roadmap for Backstage?
 
 We envision three phases, which you can learn about in
-[our project roadmap](overview/roadmap.md). Even though the open source version
+[our project roadmap](../overview/roadmap.md). Even though the open source version
 of Backstage is relatively new compared to our internal version, we have already
 begun work on various aspects of all three phases. Looking at the
 [milestones for active issues](https://github.com/backstage/backstage/milestones)

docs/faq/technical.md

@@ -51,7 +51,7 @@ type of content. Plugins all use a common set of platform APIs and reusable UI
 components. Plugins can fetch data either from the backend or an API exposed
 through the proxy.
 
-Learn more about [the different components](overview/what-is-backstage.md) that
+Learn more about [the different components](../overview/what-is-backstage.md) that
 make up Backstage.
 
 ### Why can't I dynamically install plugins without modifications to the app?
@@ -188,7 +188,7 @@ data is shared with.
 Yes. The core frontend framework could be used for building any large-scale web
 application where (1) multiple teams are building separate parts of the app, and
 (2) you want the overall experience to be consistent. That being said, in
-[Phase 2](overview/roadmap.md) of the project we will add features that are
+[Phase 2](../overview/roadmap.md) of the project we will add features that are
 needed for developer portals and systems for managing software ecosystems. Our
 ambition will be to keep Backstage modular.