Update CONTRIBUTING.md

Fixed some grammar issues.

CONTRIBUTING.md

@@ -1,14 +1,14 @@
 Thank you very much for your every contributions!
 
-I'm very glad to see so many changes and advances from earlier SDK.
+I'm very glad to see so many changes and advances from the earlier SDK.
 
-While getting lots of information from you, entire network in repo doesn't seem very clear
+While getting lots of information from you, the entire network in repo doesn't seem very clear
 so the work was very hard to be carried out so far.
 
 Hence, I will update some GUIDELINES that is very necessary to get your ideas be MERGED.
 
 1. After every release, there is a 'develop' branch. To make your idea be accepted on the next release,
-YOU SHOULD GET PULL REQUEST BASED ON 'DEVELOP' BRANCH, NOT 'MASTER' BRANCH!!
+YOU SHOULD GET PULL REQUEST BASED ON THE 'DEVELOP' BRANCH, NOT THE 'MASTER' BRANCH!!
 All pull requests based on 'master' branch will be 'suspended' or 'won't fix', so make sure before the pull request.
 
 2. I'm hoping that many users can list up on the [CONTRIBUTORS](https://github.com/ROBOTIS-GIT/DynamixelSDK/graphs/contributors).