Warn if an invalid command is entered

Some small UI changes

Co-authored-by: DeepBlueV7.X <nicolas.werner@hotmail.de>

fixes #1406

Update Arch Linux installation instructions

nheko Arch Linux package is now available in community repository, AUR
isn't needed anymore to install it.

Currently translated at 100.0% (942 of 942 strings)

Co-authored-by: Chen Shaoju <oshirisu.red@gmail.com>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/zh_Hans/
Translation: Nheko/nheko

Fixes #1297

Fixes #1363

Please note that this doesn't prompt when you try to send a message with a bad command.

Currently translated at 47.8% (451 of 942 strings)

Co-authored-by: NullPointerException <kigen745@gmail.com>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/uk/
Translation: Nheko/nheko

Create github release from tags and upload artifacts as assets