Clarify warning messages

source/derelict/vulkan/package.d

@@ -39,9 +39,9 @@ private {
 }
 
 static if (libNames.length == 0) {
-  pragma(msg, "Library names don't specified for this system."
-            , " Please, specify it on library loading. e.g:\n"
-            , "DerelictVulkan.load(\"libvulkan.so\");");
+  pragma(msg, "Library names are not specified for this system, "
+            , "please specify them when loading the library. "
+            , "Example: DerelictVulkan.load(\"libvulkan.so\");");
 }
 
 class DerelictVulkanLoader : SharedLibLoader {

source/derelict/vulkan/system/dummy.d

@@ -29,8 +29,8 @@ DEALINGS IN THE SOFTWARE.
 module derelict.vulkan.system.dummy;
 
 mixin template SystemFunctionality() {
-  pragma(msg, "Non of currently supported systems was fit to yours. "
-            , "If required functionality is missed, feel free to extend and share on GitHub.");
+  pragma(msg, "This system is not supported. "
+            , "Please feel free to extend and submit a pull request.");
   enum libNames = "";
   mixin template Functions() {
     pragma(inline, true)