Be a bit more expressive on the config lookup

There is a series of checks for the plugin config file now.
Thanks to Bo who added this. This commit connects the respective
code path with the doc string for an easier read

kiwi_boxed_plugin/defaults.py

@@ -41,35 +41,40 @@ def get_plugin_config_file() -> str:
         """
         Config file name: `kiwi_boxed_plugin.yml`
         Locations are searched in this order:
-            1. Environment variable "KIWI_BOXED_PLUGIN_CFG" (full path, name can be different)
-            2. Current directory
+            1. ENV variable: $KIWI_BOXED_PLUGIN_CFG
+               full path to file, name is freely selectable
+            2. $PWD/kiwi_boxed_plugin.yml
             3. $HOME/.config/kiwi/kiwi_boxed_plugin.yml
             4. /etc/kiwi_boxed_plugin.yml
             5. Resource (default config, coming with the package)
         """
-        cfg_n = "kiwi_boxed_plugin.yml"
+        config_name = "kiwi_boxed_plugin.yml"
 
-        # Path via env. Here is no limit what name/path of the cfg
-        cfg_p: str | None = os.environ.get("KIWI_BOXED_PLUGIN_CFG")
-        if cfg_p is not None and os.path.exists(cfg_p):
-            return cfg_p
+        # 1.
+        config_path_env: str | None = os.environ.get("KIWI_BOXED_PLUGIN_CFG")
+        if config_path_env is not None and os.path.exists(config_path_env):
+            return config_path_env
 
-        # Curr dir
-        cfg_p = os.path.abspath(cfg_n)
-        if os.path.exists(cfg_p):
-            return cfg_p
+        # 2.
+        config_path_pwd = os.path.abspath(config_name)
+        if os.path.exists(config_path_pwd):
+            return config_path_pwd
 
-        # Local Kiwi config
-        cfg_pth: pathlib.Path = pathlib.Path.home().joinpath(f".config/kiwi/{cfg_n}")
-        if cfg_pth.exists():
-            return cfg_pth.as_posix()
+        # 3.
+        config_path_home: pathlib.Path = pathlib.Path.home().joinpath(
+            f'.config/kiwi/{config_name}'
+        )
+        if config_path_home.exists():
+            return config_path_home.as_posix()
 
-        cfg_p = f"/etc/{cfg_n}"
-        if os.path.exists(cfg_p):
-            return cfg_p
+        # 4.
+        config_path_system = f'/etc/{config_name}'
+        if os.path.exists(config_path_system):
+            return config_path_system
 
+        # 5.
         return resource_filename(
-            'kiwi_boxed_plugin', f'config/{cfg_n}'
+            'kiwi_boxed_plugin', f'config/{config_name}'
         )
 
     @staticmethod