[clang] [NFC][analyzer][docs] Document MallocChecker's ownership attributes (PR #121759)

[Balazs Benics via cfe-commits]

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@@ -1389,6 +1389,68 @@ Query for this attribute with ``__has_attribute(overloadable)``.
   }];
 }
 
+def OwnershipDocs : Documentation {
+  let Heading = "ownership_holds, ownership_returns, ownership_takes (Clang "
+                "Static Analyzer)";
+  let Category = DocCatFunction;
+  let Content = [{
+
+.. note::
+
+  In order for the Clang Static Analyzer to acknowledge these attributes, the
+  ``Optimistic`` config needs to be set to true for the checker
+  ``unix.DynamicMemoryModeling``:
+
+  ``-Xclang -analyzer-config -Xclang unix.DynamicMemoryModeling:Optimistic=true``
+
+These attributes are used by the Clang Static Analyzer's dynamic memory modeling
+facilities to mark custom allocating/deallocating functions.
+
+All 3 attributes' first parameter of type string is the type of the allocation:
+``malloc``, ``new``, etc. to allow for catching mismatched deallocation bugs to
+be found.
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steakhal wrote:

Here I'm not exactly sure what `etc` refers to. Is the set of accepted values here backed in or it can be the name of any previously declared function? Or even any identifier?

https://github.com/llvm/llvm-project/pull/121759