feat: add bats tests, docs (#139)

* fix(test): ensure bats file list uses xargs

* docs(readme): use yarn for testing instructions

* fix(test): ensure pipelines fail properly

* docs(alias): fix table header

---------

Signed-off-by: Ismo Vuorinen <ismo@ivuorinen.net>

local/bin/x-change-alacritty-theme.md

@@ -0,0 +1,20 @@
+# x-change-alacritty-theme
+
+Adapted from <https://gist.github.com/xqm32/17777d035930d622d0ff7530bfab61fd>
+
+## Usage
+
+```bash
+x-change-alacritty-theme <day|night>
+```
+
+Switches Alacritty's theme by copying a theme file under
+`~/.config/alacritty/`.
+
+### Example
+
+```bash
+x-change-alacritty-theme night
+```
+
+<!-- vim: set ft=markdown spell spelllang=en_us cc=80 : -->