fix: fix cppdoc main page (#80)

Author: Sudrut

src/content/docs/index.mdx

@@ -8,7 +8,7 @@ hero:
     file: ../../assets/cpp-logo.svg
   actions:
     - text: Reference
-      link: /cpp/language/basics
+      link: /cpp/language/basics/
       variant: primary
       icon: right-arrow
     - text: GitHub Repository
@@ -22,8 +22,8 @@ banner:
 import { LinkCard, CardGrid } from '@astrojs/starlight/components';
 
 <CardGrid>
-  <LinkCard title="C++ Language Reference" href="/cpp/language/basics" />
-  <LinkCard title="C++ Library Reference" href="/cpp/library" />
-  <LinkCard title="C Language Reference" href="/c/language/basic" />
+  <LinkCard title="C++ Language Reference" href="/cpp/language/basics/" />
+  <LinkCard title="C++ Library Reference" href="/cpp/library/" />
+  <LinkCard title="C Language Reference" href="/c/language/basic_concepts/" />
   <LinkCard title="C Library Reference" />
 </CardGrid>