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/ae.md

@@ -0,0 +1,19 @@
+# ae
+
+Encrypt a file with `age` using your GitHub SSH keys.
+
+## Usage
+
+```bash
+ae <file>
+```
+
+Uses `AGE_KEYSFILE` and `AGE_KEYSSOURCE` if keys are missing.
+
+## Example
+
+```bash
+ae secret.txt
+```
+
+<!-- vim: set ft=markdown spell spelllang=en_us cc=80 : -->