Updated URLs after opencost.io/docs/ rearrangement.

Signed-off-by: Matt Ray <github@mattray.dev>

PROMETHEUS.md

@@ -1 +1 @@
-Available at <https://www.opencost.io/docs/prometheus>
+Available at <https://www.opencost.io/docs/installation/prometheus>

ROADMAP.md

@@ -8,7 +8,7 @@ __2023 roadmap__
 * Add external cloud asset cost monitoring ([see the current working group](https://docs.google.com/document/d/1-d-Vvy1VGHW0sXKiTjTplIUEnrElIlnfMU8sUpEehlA/edit#heading=h.vmcygvd1xmbm))
 * More accessible & improved user interface
 * Continued improvement of the [OpenCost Helm chart](https://github.com/opencost/opencost-helm-chart)
-* More robust [API documentation](https://www.opencost.io/api) and examples.
+* More robust [API documentation](https://www.opencost.io/docs/integrations/api) and examples.
 * Expose carbon emission ratings
 
 Please contact us at opencost@kubecost.com if you're interest in more detail.