chore: document exports

package.json

@@ -32,6 +32,7 @@
   "keywords": [
     "syslog",
     "optional",
-    "windows"
+    "windows",
+    "posix"
   ]
 }

readme.md

@@ -2,8 +2,11 @@
 
 # About
 
-This package installs modern-syslog as an optional dependency for ease of use on Windows and exposes some of its API including a compatibility layer for users of the POSIX package.
-Syslog constants are used from [syslog-constants](https://www.npmjs.com/package/syslog-constants).
+This package installs [modern-syslog](https://www.npmjs.com/package/modern-syslog) as an optional dependency for ease of use on Windows (via a stub) and exposes some of its API.
+
+There is also a compatiblity layer for users of the [posix](https://www.npmjs.com/package/posix) package (syslog related functions, drop-in replacement).
+
+Constants are provided by [syslog-constants](https://www.npmjs.com/package/syslog-constants) and are always available.
 
 # Usage
 
@@ -12,3 +15,51 @@ Install using npm:
 ```
 $ npm install optional-syslog
 ```
+
+Replace
+```
+require('modern-syslog');
+```
+or
+```
+require('posix');
+```
+
+with
+```
+require('optional-syslog');
+```
+
+# Exported properties and methods
+
+## syslog-constants (except named as in modern-syslog)
+
+* facility
+* level
+* option
+
+Documentation at https://www.npmjs.com/package/syslog-constants#properties
+
+## modern-syslog
+
+* log
+* open
+* close
+* upto
+* setmask
+
+Documentation at https://www.npmjs.com/package/modern-syslog#api
+
+Not provided are:
+* formatted versions of `log()`
+* streaming API
+* curmask (since it's a read operation and can't be noop'd)
+
+## posix
+
+* openlog
+* closelog
+* setlogmask
+* syslog
+
+Documentation at https://www.npmjs.com/package/posix#syslog