doc: minor changes

docs/md/core.md

@@ -140,7 +140,7 @@ constexpr auto str = "text"_hs;
 Finally, in case users need to create hashed strings at runtime, this class also
 offers the necessary functionalities:
 
-```
+```cpp
 std::string orig{"text"};
 
 // create a full-featured hashed string...
@@ -219,7 +219,7 @@ otherwise.
 A type info object is an opaque class that is also copy and move constructible.
 This class is returned by the `type_id` function template:
 
-```
+```cpp
 // generates an info object from a type ...
 auto info = entt::type_id<a_type>();
 

docs/md/entity.md

@@ -848,7 +848,7 @@ even though it requires users to set up their own stamping functions.
 The best bet here is probably to define a reflection system or a mapping between
 the type identifiers and their opaque functions for stamping. As an example:
 
-```
+```cpp
 template<typename Type>
 void stamp(const entt::registry &from, const entt::entity src, entt::registry &to, const entt::entity dst) {
     to.emplace_or_replace<Type>(dst, from.get<Type>(src));

docs/md/signal.md

@@ -149,7 +149,7 @@ If they are not, the first argument of the function type must be that of the
 class on which the members operate and an instance of this class must obviously
 be passed when invoking the delegate:
 
-```
+```cpp
 entt::delegate<void(my_struct &, int)> delegate;
 delegate.connect<&my_struct::f>();