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-path.md

@@ -0,0 +1,30 @@
+# x-path
+
+Manage entries in the `PATH` variable through subcommands.
+
+## Usage
+
+```bash
+x-path <command> <directory1> [directory2 ...]
+```
+
+### Commands
+
+- `append` / `a` – Append directories to `PATH`
+- `prepend` / `p` – Prepend directories to `PATH`
+- `remove` – Remove directories from `PATH`
+- `check` – Validate directories (default: all in `PATH`)
+
+Set `VERBOSE=1` for progress output.
+
+## Examples
+
+```bash
+# Prepend /opt/bin to PATH
+x-path prepend /opt/bin
+
+# Remove /usr/local/bin from PATH
+x-path remove /usr/local/bin
+```
+
+<!-- vim: set ft=markdown spell spelllang=en_us cc=80 : -->