Improve clarity of instructions for new contributors

Fix some typos and grammar
Some rewording
Clarifying how to make a more useful bug report

CONTRIBUTING.md

@@ -4,31 +4,36 @@ and follow this short guide.
 
 # Reporting Issues
 Before you open an issue on GitHub, please discuss it on one of our
-[mailing lists](https://jitsi.org/Development/MailingLists) and wait for a confirmation
-from one of the comitters. If you have that permission, please be as precise as possible.
-Mention the version of Jitsi you are using, your operating system and explain how the
-problem can be reproduced.
-
-Please note that issues that are reported against a version older than the current stable
-release will be closed without further investigation.
+[mailing lists](https://jitsi.org/Development/MailingLists) and wait for a 
+confirmation from one of the committers. Once you have that confirmation, 
+please proceed to reporting the issue on Github, while providing as much 
+information as possible. Mention the version of Jitsi you are using, your 
+operating system and explain how the problem can be reproduced.
+
+Please note that issues that are reported against a version older than the 
+current stable release will be closed without further investigation. If you 
+discover however that the issue also exists in an older version, this is 
+useful information. Even more useful is to know if it worked in a specific 
+version and stopped working in a subsequent version. This will help 
+developers pinpoint the issue. Also useful is to test the nightly build.
 
 # Translation
 Please go to our [translation website](http://translate.jitsi.org), which is a
 [Pootle](http://pootle.translatehouse.org/) instance that allows for easy
-online translation. Many languages are already there and wait for completion.
+online translation. Many languages are already there and waiting for completion.
 
 If your preferred language is not yet created, please drop us an
 [e-mail](mailto:dev@jitsi.org). Be aware though that completing a new language
-will be quite some effort, so be sure you actually want to take up on that
+will be quite some effort, so be sure you actually want to take on that
 work and translate more than a few words.
 
 Please do not create any pull requests for the resources_XX.properties files,
-they will be overwritten with what comes from
+as they will be overwritten with what comes from
 [Pootle](http://translate.jitsi.org). The only exception is if you find
 mistakes in the language file for
 [English](https://github.com/jitsi/jitsi/blob/master/resources/languages/resources.properties).
 
-For some more information, e.g. how to translate offline visit the
+For more information, e.g. how to translate offline visit the
 [How To Translate Jitsi](https://jitsi.org/Documentation/HowToTranslateSIPCommunicator)
 on our website.