Doc: Add docs for Utils::Environment::systemEnvironment()

Because we link to it from the Utils namespace docs.

Change-Id: I4d320b34687e7a6304cbedcbf7e2e5d3a43642b6
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/utils/environment.cpp

@@ -12,6 +12,13 @@
 #include <QReadWriteLock>
 #include <QSet>
 
+/*!
+    \class Utils::Environment
+    \inmodule QtCreator
+
+    \brief The Environment class sets \QC's system environment.
+*/
+
 namespace Utils {
 
 static QReadWriteLock s_envMutex;
@@ -184,6 +191,14 @@ void Environment::prependOrSetLibrarySearchPaths(const FilePaths &values)
     });
 }
 
+/*!
+    Returns \QC's system environment.
+
+    This can be different from the system environment that \QC started in if the
+    user changed it in \uicontrol Preferences > \uicontrol Environment >
+    \uicontrol System > \uicontrol Environment.
+*/
+
 Environment Environment::systemEnvironment()
 {
     QReadLocker lock(&s_envMutex);