Fix more bad links (#551)

Author: davidkonigsberg

fern/products/ask-fern/pages/getting-started/what-is-ask-fern.mdx

@@ -27,7 +27,7 @@ Ask Fern is Fern's AI Search feature that indexes your documentation and provide
   <Card 
     title="Custom prompting"
     icon="regular book-open"
-    href="/learn/ai-search/custom-prompting"
+    href="/learn/ask-fern/configuration/custom-prompts"
   >
     Tailor Ask Fern behavior to your users' needs. 
   </Card>
@@ -43,15 +43,15 @@ Ask Fern is Fern's AI Search feature that indexes your documentation and provide
   <Card 
     title="Guidance" 
     icon="regular fa-question-circle"
-    href="/learn/ask-fern/features/guidance" 
+    href="/learn/ask-fern/configuration/guidance" 
     >
     Add custom FAQs to Ask Fern. 
   </Card>
 
   <Card 
     title="Documents" 
     icon="regular file-alt"
-    href="/learn/ask-fern/features/documents" 
+    href="/learn/ask-fern/configuration/documents" 
     >
     Add custom documents to Ask Fern. 
   </Card>

fern/products/home/pages/welcome.mdx

@@ -203,7 +203,7 @@ import { FernFooter } from "../../../components/FernFooter";
             <img src="./images/arrow-right-white.svg" alt="Arrow right light" className="dark:hidden" noZoom />
             <img src="./images/arrow-right-black.svg" alt="Arrow right light" className="hidden dark:block" noZoom />
           </a>
-          <a className="fern-button minimal normal gap-1 a-btn" href="/ask-fern/configuration/custom-prompting">
+          <a className="fern-button minimal normal gap-1 a-btn" href="/ask-fern/configuration/custom-prompts">
             Configure
             <img src="./images/arrow-right-black.svg" alt="Arrow right light" className="dark:hidden" noZoom />
             <img src="./images/arrow-right-white.svg" alt="Arrow right light" className="hidden dark:block" noZoom />