[clang-tidy][NFC] Update documentation for bugprone-undefined-memory-manipulation

Add example and more information to check documentation.

Author: PiotrZSL

clang-tools-extra/clang-tidy/bugprone/UndefinedMemoryManipulationCheck.h

@@ -14,7 +14,7 @@
 namespace clang::tidy::bugprone {
 
 /// Finds calls of memory manipulation functions ``memset()``, ``memcpy()`` and
-/// ``memmove()`` on not TriviallyCopyable objects resulting in undefined
+/// ``memmove()`` on non-TriviallyCopyable objects resulting in undefined
 /// behavior.
 ///
 /// For the user-facing documentation see:

clang-tools-extra/docs/clang-tidy/checks/bugprone/undefined-memory-manipulation.rst

@@ -4,4 +4,31 @@ bugprone-undefined-memory-manipulation
 ======================================
 
 Finds calls of memory manipulation functions ``memset()``, ``memcpy()`` and
-``memmove()`` on not TriviallyCopyable objects resulting in undefined behavior.
+``memmove()`` on non-TriviallyCopyable objects resulting in undefined behavior.
+
+Using memory manipulation functions on non-TriviallyCopyable objects can lead
+to a range of subtle and challenging issues in C++ code. The most immediate
+concern is the potential for undefined behavior, where the state of the object
+may become corrupted or invalid. This can manifest as crashes, data corruption,
+or unexpected behavior at runtime, making it challenging to identify and
+diagnose the root cause. Additionally, misuse of memory manipulation functions
+can bypass essential object-specific operations, such as constructors and
+destructors, leading to resource leaks or improper initialization.
+
+For example, when using ``memcpy`` to copy ``std::string``, pointer data is
+being copied, and it can result in a double free issue.
+
+.. code-block:: c++
+
+  #include <cstring>
+  #include <string>
+
+  int main() {
+      std::string source = "Hello";
+      std::string destination;
+
+      std::memcpy(&destination, &source, sizeof(std::string));
+
+      // Undefined behavior may occur here, during std::string destructor call.
+      return 0;
+  }