Add abra docs

docs/abra.md

@@ -0,0 +1,34 @@
+---
+title: Abra
+---
+
+## Enable auto-completion
+
+### Bash
+
+Copy `scripts/autocomplete/bash` into `/etc/bash_completion.d/` and rename
+it to abra.
+
+```
+sudo cp scripts/autocomplete/bash /etc/bash_completion.d/abra
+source /etc/bash_completion.d/abra
+```
+
+In development, you can source the script in your git checkout, just make sure
+to set `PROG=abra`, otherwise it'll add completion to the wrong command:
+
+```
+PROG=abra source /path/to/abra/scripts/autocomplete/bash
+```
+
+### (Fi)Zsh
+
+(fi)zsh doesn't have an autocompletion folder by default but you can create one, then copy `scripts/autocomplete/zsh` into it and add a couple lines to your `~/.zshrc` or `~/.fizsh/.fizshrc`
+
+```
+sudo mkdir /etc/zsh/completion.d/
+sudo cp scripts/autocomplete/zsh /etc/zsh/completion.d/abra
+echo "PROG=abra\n_CLI_ZSH_AUTOCOMPLETE_HACK=1\nsource /etc/zsh/completion.d/abra" >> ~/.zshrc
+```
+
+(replace .zshrc with ~/.fizsh/.fizshrc if you use fizsh)