Update README.md

README.md

@@ -80,10 +80,12 @@ Bar the things.
 cmd config
 cmd config KEY
 cmd config KEY VALUE
+cmd config KEY ""
 ```
 
 The `config` command is for reading, writing, and displaying standard
-open desktop configuration properties. 
+open desktop configuration properties. Pass an empty string to delete
+a property.
 
 ### Arguments
 
@@ -91,12 +93,28 @@ With no arguments outputs all the currently cached configuration
 settings. 
 
 With a single KEY argument fetches the value for that key and outputs
-it.
+it. The special `dir` KEY is reserved and always outputs the full path
+to the current configuration directory containing the `values` file. The
+special `path` KEY is reserved and always outputs the full path to the
+`values` file itself.
 
 With more than one argument the remaining arguments after the KEY will
 be combined into the VALUE and written to a `values` file in the
-standard configuration home location (Search for `XDG_CONFIG_HOME` for
-more information).  
+configuration directory. 
+
+### Configuration Directory
+
+The configuration directory path relies on the following environment
+variables:
+
+* `EXE` - defaults to name of currently running command (cmd)
+* `HOME` - checked for `$HOME/.config/$EXE/values`
+* `XDG_CONFIG_HOME` - overrides `$HOME/.config`
+* `CONFIG_DIR` - full path to directory containing `values` file
+
+The `CONFIG_DIR` always takes priority over anything else if set, but is
+never implied. If the directory does not exist it will be created the
+first time a value is set.
 
 ### Configuration `values` File Format
 
@@ -161,5 +179,5 @@ Displays a summary of usage.
 
 ----
 
-*Autogenerated Mon Aug 23 10:26:57 PM EDT 2021*
+*Autogenerated Wed Aug 25 12:52:34 AM EDT 2021*