Addressed internal review comments:

* Clarify that the destination directory will be created/cleaned up.
* Clarified that build.py should work with Mendix 8, 9 and 10 MPRs/MPKs.

Author: zlogic

README.md

@@ -97,7 +97,7 @@ When building the the `rootfs-builder.dockerfile` file, you can provide the foll
 
 If your app is a source MPK file, an MPR project directory or a compressed MDA file, it needs to be converted or compiled into a format supported by CF Buildpack - an extracted MDA file.
 
-This feature is available in Docker Buildpack version v5.1.0 and later, and is intended to allow building Mendix 10 apps in custom CI/CD pipelines.
+This feature is available in Docker Buildpack version v6.0.0 and later, and is intended to allow building Mendix 8, 9 and 10 apps in custom CI/CD pipelines.
 
 To do this, run:
 

upgrading-from-v5.md

@@ -14,7 +14,7 @@ If you're upgrading from Docker Buildpack v4 (or an older version), you'll also
 Docker Buildpack v6 no longer uses CF Buildpack to compile MPR (or MPK) files - to continue supporting newer versions of Mendix, Java and the base OS.
 Instead, a custom `build.py` script will:
 
-1. Prepare a clean [Docker context](https://docs.docker.com/build/concepts/context/) in the path specified by `--destination`. All files required to build the app image will be copied to this destination.
+1. Prepare a clean [Docker context](https://docs.docker.com/build/concepts/context/) in the path specified by `--destination`. All files required to build the app image will be copied to this destination. If the directory doesn't exist, the `build.py` script will create it; if the directory is not empty, `build.py` will delete its contents.
 2. Detect the file type of the source path specified by the `--source` arg (an MPK file, an MPR file, an MDA file or an unpacked MDA directory).
 3. If necessary (`--source` specifies project that needs to be compiled)
    1. Create an image containing [mxbuild](https://docs.mendix.com/refguide/mxbuild/) and its dependencies.