* Fix use of config override directory in `devenv up`

`--config-directory` is for the generate config script; `-c` is for usage

* Add homeserver config override directory to gitignore

* Newsfile

Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>

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Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>