Update readme to note debug flag needed for coverage
@@ -396,6 +396,9 @@ Code coverage has been an important metric in software testing. In Move CLI, we
address the need for code coverage information with an additional flag,
`--track-cov`, that can be passed to the `move sandbox test` command.
+Note: To view coverage information, the Move CLI must be installed with the `--debug` flag;
+i.e., `cargo install --debug --path diem/language/tools/move-cli`.
+
Using our running example to illustrate:
```shell
$ move sandbox test readme --track-cov
