Add logging instructions in a separate document (#5663)

* Add logging instructions in a separate document

* Update lib/msal-browser/docs/logging.md

Co-authored-by: Doğan Erişen <v-derisen@microsoft.com>

* Add more details for enabling logs in the browser

* Adding PCA context

* Update lib/msal-browser/docs/logging.md

Co-authored-by: Doğan Erişen <v-derisen@microsoft.com>

* Adding appropriate import code for usage example

* Correcting the import LogLevel

---------

Co-authored-by: Doğan Erişen <v-derisen@microsoft.com>

Author: sameerag

lib/msal-browser/docs/images/BrowserLogEnablement.png

@@ -0,0 +1,63 @@
+# MSAL JS logging instructions
+
+These are steps needed to enable MSAL JS logging for your applications:
+
+1. In the MSAL [Configuration](./configuration.md) object, you can enable logging to collect msal js logs. We enable different levels of logging and an appropriate level can be chosen as needed. 
+
+2. The logger options can be set as below, the example chooses `LogLevel.Trace`
+
+```javascript
+
+import { PublicClientApplication, LogLevel } from "@azure/msal-browser";
+
+const msalConfig = {
+    auth: {
+        ...
+    },
+    cache: {
+        ...
+    },
+    system: {
+        loggerOptions: {
+            logLevel: LogLevel.Trace,
+            loggerCallback: (level, message, containsPii) => {
+                if (containsPii) {	
+                    return;	
+                }
+                switch (level) {	
+                    case LogLevel.Error:	
+                        console.error(message);	
+                        return;	
+                    case LogLevel.Info:	
+                        console.info(message);	
+                        return;	
+                    case LogLevel.Verbose:	
+                        console.debug(message);	
+                        return;	
+                    case LogLevel.Warning:	
+                        console.warn(message);	
+                        return;	
+                    default:
+                        console.log(message);
+                        return;
+                }    
+            }
+        }
+    },
+
+    ...
+}
+
+const msalInstance = new PublicClientApplication(msalConfig);      
+
+```
+
+An example usage in a sample can be accessed [here](https://github.com/AzureAD/microsoft-authentication-library-for-js/blob/dev/samples/msal-browser-samples/VanillaJSTestApp2.0/app/default/authConfig.js#:~:text=logLevel%3A%20msal.LogLevel.Trace%2C).
+
+
+3. Make sure you have the appropriate log level enabled in your browser console to see these logs, eg: "verbose" may need to be enabled for the browser to load these.
+
+    ![browser console](./images/BrowserLogEnablement.png)
+
+
+