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-dfm-docs-xterm-keybindings.md

@@ -0,0 +1,14 @@
+# x-dfm-docs-xterm-keybindings
+
+Generate `docs/tmux-keybindings.md` using tmux's key list.
+
+## Usage
+
+```bash
+x-dfm-docs-xterm-keybindings
+```
+
+No parameters are needed. The script writes the file under `docs/` and
+overwrites any existing version.
+
+<!-- vim: set ft=markdown spell spelllang=en_us cc=80 : -->