Extend internal API docs, part 2

Picking up from #8111.

Co-authored-by: Eelco Dolstra <edolstra@gmail.com>

src/libutil/config.hh

@@ -124,21 +124,21 @@ public:
     void reapplyUnknownSettings();
 };
 
-/* A class to simplify providing configuration settings. The typical
-   use is to inherit Config and add Setting<T> members:
-
-   class MyClass : private Config
-   {
-     Setting<int> foo{this, 123, "foo", "the number of foos to use"};
-     Setting<std::string> bar{this, "blabla", "bar", "the name of the bar"};
-
-     MyClass() : Config(readConfigFile("/etc/my-app.conf"))
-     {
-       std::cout << foo << "\n"; // will print 123 unless overridden
-     }
-   };
-*/
-
+/**
+ * A class to simplify providing configuration settings. The typical
+ * use is to inherit Config and add Setting<T> members:
+ *
+ * class MyClass : private Config
+ * {
+ *   Setting<int> foo{this, 123, "foo", "the number of foos to use"};
+ *   Setting<std::string> bar{this, "blabla", "bar", "the name of the bar"};
+ *
+ *   MyClass() : Config(readConfigFile("/etc/my-app.conf"))
+ *   {
+ *     std::cout << foo << "\n"; // will print 123 unless overridden
+ *   }
+ * };
+ */
 class Config : public AbstractConfig
 {
     friend class AbstractSetting;
@@ -228,7 +228,9 @@ protected:
     bool isOverridden() const { return overridden; }
 };
 
-/* A setting of type T. */
+/**
+ * A setting of type T.
+ */
 template<typename T>
 class BaseSetting : public AbstractSetting
 {
@@ -311,8 +313,10 @@ public:
     void operator =(const T & v) { this->assign(v); }
 };
 
-/* A special setting for Paths. These are automatically canonicalised
-   (e.g. "/foo//bar/" becomes "/foo/bar"). */
+/**
+ * A special setting for Paths. These are automatically canonicalised
+ * (e.g. "/foo//bar/" becomes "/foo/bar").
+ */
 class PathSetting : public BaseSetting<Path>
 {
     bool allowEmpty;