[Minor] Fix some docs

src/libutil/cxx/util.hxx

@@ -40,6 +40,15 @@ constexpr auto array_of(Ts &&...t) -> std::array<typename std::decay_t<typename
 	return {{std::forward<T>(t)...}};
 }
 
+/**
+ * Find a value in a map
+ * @tparam C Map type
+ * @tparam K Key type
+ * @tparam V Value type
+ * @param c Map to search
+ * @param k Key to search
+ * @return Value if found or std::nullopt otherwise
+ */
 template<class C, class K, class V = typename C::mapped_type, typename std::enable_if_t<std::is_constructible_v<typename C::key_type, K> && std::is_constructible_v<typename C::mapped_type, V>, bool> = false>
 constexpr auto find_map(const C &c, const K &k) -> std::optional<std::reference_wrapper<const V>>
 {
@@ -93,17 +102,18 @@ inline auto string_foreach_line(const S &input, const F &functor)
 
 /**
  * Iterate over elements in a string
- * @tparam S
- * @tparam F
- * @param input
- * @param delim
- * @param functor
- * @param ignore_empty
- * @return
+ * @tparam S string type
+ * @tparam D delimiter type
+ * @tparam F functor type
+ * @param input string to iterate
+ * @param delim delimiter to use
+ * @param functor functor to call
+ * @param ignore_empty ignore empty elements
+ * @return nothing
  */
 template<class S, class D, class F,
 		 typename std::enable_if_t<std::is_invocable_v<F, std::string_view> && std::is_constructible_v<std::string_view, S> && std::is_constructible_v<std::string_view, D>, bool> = true>
-inline auto string_foreach_delim(const S &input, const D &delim, const F &functor, const bool ignore_empty = true)
+inline auto string_foreach_delim(const S &input, const D &delim, const F &functor, const bool ignore_empty = true) -> void
 {
 	size_t first = 0;
 	auto sv_input = std::string_view{input};
@@ -124,6 +134,13 @@ inline auto string_foreach_delim(const S &input, const D &delim, const F &functo
 	}
 }
 
+/**
+ * Split string on a character
+ * @tparam S string type
+ * @param input string to split
+ * @param chr character to split on
+ * @return pair of strings
+ */
 template<class S, typename std::enable_if_t<std::is_constructible_v<std::string_view, S>, bool> = true>
 inline auto string_split_on(const S &input, std::string_view::value_type chr) -> std::pair<std::string_view, std::string_view>
 {
@@ -144,6 +161,10 @@ inline auto string_split_on(const S &input, std::string_view::value_type chr) ->
 
 /**
  * Enumerate for range loop
+ * @tparam T iterable type
+ * @tparam TIter iterator type
+ * @param iterable iterable object
+ * @return iterator object
  */
 template<typename T,
 		 typename TIter = decltype(std::begin(std::declval<T>())),