Document readConfig function (#3230)

* Update getConfig.md

* Create readConfig.md

* Update getConfig.md

* Update readConfig.md

Co-authored-by: MartianTribe <steve@martiantribe.com>

dev-docs/publisher-api-reference/getConfig.md

@@ -4,8 +4,9 @@ title: pbjs.getConfig([string])
 description: 
 ---
 
+## Overview
 
-The `getConfig` function is for retrieving the current configuration object or subscribing to configuration updates. When called with no parameters, the entire config object is returned. When called with a string parameter, a single configuration property matching that parameter is returned.
+The `getConfig` function is used for retrieving the current configuration object or subscribing to configuration updates. When called with no parameters, the entire config object is returned. When called with a string parameter, a single configuration property matching that parameter is returned. Be careful with use of this function, as it returns a reference to the configuration instead of a clone. The readConfig function has been introduced for safer use. 
 
 {% highlight js %}
 /* Get config object */
@@ -15,7 +16,10 @@ config.getConfig()
 config.getConfig('debug')
 {% endhighlight %}
 
-The `getConfig` function also contains a 'subscribe' ability that adds a callback function to a set of listeners that are invoked whenever `setConfig` is called. The subscribed function will be passed the options object that was used in the `setConfig` call. Individual topics can be subscribed to by passing a string as the first parameter and a callback function as the second.  For example:
+
+### Subscribe
+
+The `getConfig` function contains a `subscribe` feature that adds a callback function to a set of listeners that are invoked whenever `setConfig` is called. The `subscribed` function will be passed the `options` object that was used in the `setConfig` call. Individual topics can be subscribed to by passing a string as the first parameter and a callback function as the second.  For example:
 
 {% highlight js %}
 
@@ -31,4 +35,4 @@ unsubscribe(); // no longer listening
 
 {% endhighlight %}
 
-<hr class="full-rule" />
+<hr class="full-rule" />

dev-docs/publisher-api-reference/readConfig.md

@@ -0,0 +1,18 @@
+---
+layout: api_prebidjs
+title: pbjs.readConfig([string])
+description: 
+---
+
+
+The `readConfig` function is used for retrieving the current configuration object or subscribing to configuration updates. When called with no parameters, the entire config object is returned. When called with a string parameter, a single configuration property matching that parameter is returned.  The readConfig function has been introduced for safer use of the getConfig functionality, as it returns a clone. 
+
+{% highlight js %}
+/* Get config object */
+config.readConfig()
+
+/* Get debug config */
+config.readConfig('debug')
+{% endhighlight %}
+
+<hr class="full-rule" />