[INTERNAL] Introduce UI5_DATA_DIR env (#855)

JIRA: CPOUI5FOUNDATION-703

---------

Co-authored-by: Günter Klatt <[email protected]>

Author: d3xter666

docs/pages/Troubleshooting.md

@@ -51,4 +51,19 @@ UI5 + Karma:
 
 
 !!! warning
-    The combination of the `UI5_LOG_LVL` environment variable with the `--log-level` CLI parameter might lead to unexpected results; they should be used interchangeably but not together. The CLI parameter takes precedence over the `UI5_LOG_LVL` environment variable.
+    The combination of the `UI5_LOG_LVL` environment variable with the `--log-level` CLI parameter might lead to unexpected results; they should be used interchangeably but not together. The CLI parameter takes precedence over the `UI5_LOG_LVL` environment variable.
+
+### Changing UI5 Tooling's Data Directory
+
+UI5 Tooling's data directory is by default at `~/.ui5`. It's the place where the framework artefacts are stored.
+In some cases and environments this is not a convenient location and the user needs to provide a better one. The path to it is provided via the `UI5_DATA_DIR` environment variable.
+
+Example:
+
+Unix-style:
+
+`UI5_DATA_DIR=/my/custom/location/ ui5 build`
+
+On Windows:
+
+`set UI5_DATA_DIR="C:\\my\\custom\\location" ui5 build`