Turn documentation comment of module_::add_object into valid doxygen documentation

Author: YannickJadoul

docs/Doxyfile

@@ -19,4 +19,5 @@ QUIET                  = YES
 WARNINGS               = YES
 WARN_IF_UNDOCUMENTED   = NO
 PREDEFINED             = DOXYGEN_SHOULD_SKIP_THIS \
-                         PY_MAJOR_VERSION=3
+                         PY_MAJOR_VERSION=3 \
+                         PYBIND11_NOINLINE

include/pybind11/pybind11.h

@@ -944,11 +944,13 @@ class module_ : public object {
         *this = reinterpret_steal<module_>(obj);
     }
 
-    // Adds an object to the module using the given name.  Throws if an object with the given name
-    // already exists.
-    //
-    // overwrite should almost always be false: attempting to overwrite objects that pybind11 has
-    // established will, in most cases, break things.
+    /** \rst
+        Adds an object to the module using the given name.  Throws if an object with the given name
+        already exists.
+
+        ``overwrite`` should almost always be false: attempting to overwrite objects that pybind11 has
+        established will, in most cases, break things.
+    \endrst */
     PYBIND11_NOINLINE void add_object(const char *name, handle obj, bool overwrite = false) {
         if (!overwrite && hasattr(*this, name))
             pybind11_fail("Error during initialization: multiple incompatible definitions with name \"" +