Clarify JUCE 8 requirement when pluginval is a dependency [ci skip]

Author: sudara

README.md

@@ -34,7 +34,7 @@ cmake --build Builds/Debug --config Debug # build
 
 ### Including within an existing JUCE project
 
-Instead of running as a separate app, you can add pluginval as a CMake target to your existing plugin project. This not only makes for a convenient debugging workflow, it gives you better stack traces.
+Instead of running as a separate app, you can add pluginval as a CMake target to your existing JUCE plugin project. This not only makes for a convenient debugging workflow, it gives you better stack traces.
 
 For example, if you add pluginval as a git submodule like so:
 ```
@@ -49,6 +49,7 @@ CPMAddPackage("gh:tracktion/pluginval#develop")
 
 Then all you need to do is call `add_subdirectory ("modules/pluginval")` in your `CMakeLists.txt`. This should be done **after** your call to `juce_add_plugin`. 
 
+Note that only JUCE 8 is currently supported/tested for this method. 
 
 ### Third-party Installation
 ###### _Chocolatey (Windows):_