docs: remove duplicate resource lines (#10411)

A repo-wide scan found 34 resource lines that link to an identical URL
as another line in the same file. Most look like content-sync artifacts
where a refreshed resource was appended but the stale one was never
removed; three were created by my earlier link fixes folding a dead URL
into an identical live one (cloudflare calls, cloudflare service
bindings, kotlinlang flow).

In each file the first occurrence is kept and only the later duplicate
is removed; no URLs or labels were modified.

Co-authored-by: Weijian He <230282609+Madin-H23@users.noreply.github.com>

roadmaps/cpp/content/pointers-and-references@DWw8NxkLpIpiOSUaZZ1oA.md

@@ -5,5 +5,4 @@ Pointers and references are fundamental concepts in C++ that allow indirect acce
 Visit the following resources to learn more:
 
 - [@article@C++ Pointers](https://www.youtube.com/watch?v=slzcWKWCMBg)
-- [@article@Function Pointer in C++](https://www.scaler.com/topics/cpp/function-pointer-cpp/)
-- [@video@C++ pointers explained easy 👈](https://www.youtube.com/watch?v=slzcWKWCMBg)
+- [@article@Function Pointer in C++](https://www.scaler.com/topics/cpp/function-pointer-cpp/)