Add "refs/notes/gtm-data"
Add "refs/notes/gtm-data"

References for git time metrics (GTM)
```
[notes]
	rewriteref = refs/notes/gtm-data
```
results with Fatal error:
```Uncaught Gitonomy\Git\Exception\RuntimeException:
Unable to parse "refs/notes/gtm-data" in
/vendor/gitonomy/gitlib/src/Gitonomy/Git/ReferenceBag.php
on line 371```

gitonomy/gitlib,gitonomy/gitlib