Add warning about persistent disk overwriting changes

If the developer make changes to the new sdk before adding the persistent disk, these changes will likely be overwritten by the persistent disk. This patch adds a warning about this and points to the README section that show where the old files are accessible.

Signed-off-by: Peter Senna Tschudin peter.senna@collabora.com

docs/sdk-usage.md

@@ -48,6 +48,8 @@ See the [design](https://designs.apertis.org/private/latest/maintaining-workspac
 > **WARNING**: It is recommended to make a backup copy of your SDK before continuing.
 > **WARNING**: Configure the persistent disk on the **new** SDK before adding or changing files on the **new** SDK. Changes made to /home/user, /opt, and to /etc/cntlm.conf before configuring the persistent disk will be overwritten by the persistent disk. See the [README](https://gitlab.apertis.org/apertis/psdk/tree/apertis/v2020dev0#where-are-the-old-files-and-folders) for more details.
 
+> **WARNING**: Configure the persistent disk on the **new** SDK before adding or changing files on the **new** SDK. Changes made to /home/user, /opt, and to /etc/cntlm.conf before configuring the persistent disk will be overwritten by the persistent disk. See the [README](https://gitlab.apertis.org/apertis/psdk/tree/apertis/v2020dev0#where-are-the-old-files-and-folders) for more details.
+
 ## Upgrading to a new SDK using a persistent disk
 
 This involves two different SDK virtual machines: the *old* SDK and the *new* SDK. The suggested use is to first initialize the persistent disk on the *old* SDK, and then use the persistent disk on the *new* SDK.