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-hr.md

@@ -0,0 +1,19 @@
+# x-hr
+
+Print a horizontal rule. Useful for visually separating log output.
+
+## Usage
+
+```bash
+x-hr [character]
+```
+
+If no character is given a red `-` is used.
+
+### Example
+
+```bash
+x-hr "="
+```
+
+<!-- vim: set ft=markdown spell spelllang=en_us cc=80 : -->