Corrected grammar and rephrased a few sentences to read nicely (#641)

Signed-off-by: Alwin Doss <alwindoss84@gmail.com>

Incorporated review comments

Signed-off-by: Alwin Doss <alwindoss84@gmail.com>

Fixed grammar

Signed-off-by: Alwin Doss <alwindoss84@gmail.com>

CONTRIBUTING.md

@@ -1,24 +1,23 @@
 # Contributing to Mainflux
 
-The following is a set of guidelines for contributing to Mainflux and its libraries, which are
-hosted in the [Mainflux Organization](https://github.com/mainflux) on GitHub.
+The following is a set of guidelines to contribute to Mainflux and its libraries, which are
+hosted on the [Mainflux Organization](https://github.com/mainflux) on GitHub.
 
 This project adheres to the [Contributor Covenant 1.2](http://contributor-covenant.org/version/1/2/0).
 By participating, you are expected to uphold this code. Please report unacceptable behavior to
 [abuse@mainflux.com](mailto:abuse@mainflux.com).
 
 ## Reporting issues
 
-Reporting issues is a great way to contribute to the project. We always appreciate a well-written,
-thorough bug reports.
+Reporting issues are a great way to contribute to the project. We are perpetually grateful about a well-written,
+thorough bug report.
 
-Prior to raising a new issue, check out [our issue
-list](https://github.com/mainflux/mainflux/issues) to determine whether it already include the
-problem you are facing.
+Before raising a new issue, check [our issue
+list](https://github.com/mainflux/mainflux/issues) to determine if it already contains the
+problem that you are facing.
 
-A good bug report shouldn't leave others needing to chase you up for more information. Please try to
-be as detailed as possible. The following questions might serve as a template for writing a detailed
-reports:
+A good bug report shouldn't leave others needing to chase you for more information. Please be as detailed as possible. The following questions might serve as a template for writing a detailed
+report:
 
 - What were you trying to achieve?
 - What are the expected results?
@@ -29,16 +28,16 @@ reports:
 ## Pull requests
 
 Good pull requests (e.g. patches, improvements, new features) are a fantastic help. They should
-remain focused in scope and avoid containing unrelated commits.
+remain focused in scope and avoid unrelated commits.
 
-**Please ask first** before embarking any significant pull request (e.g. implementing new features,
+**Please ask first** before embarking on any significant pull request (e.g. implementing new features,
 refactoring code etc.), otherwise you risk spending a lot of time working on something that the
 maintainers might not want to merge into the project.
 
 Please adhere to the coding conventions used throughout the project. If in doubt, consult the
 [Effective Go](https://golang.org/doc/effective_go.html) style guide.
 
-To start contributing to the project, [fork](https://help.github.com/articles/fork-a-repo/) it,
+To contribute to the project, [fork](https://help.github.com/articles/fork-a-repo/) it,
 clone your fork repository, and configure the remotes:
 
 ```
@@ -47,7 +46,7 @@ cd mainflux
 git remote add upstream https://github.com/mainflux/mainflux.git
 ```
 
-If you cloned a while ago, get the latest changes from upstream:
+If your cloned repository is behind the upstream commits, then get the latest changes from upstream:
 
 ```
 git checkout master
@@ -63,8 +62,8 @@ git checkout -b MF-[issue-number]
 
 Commit your changes in logical chunks. When you are ready to commit, make sure
 to write a Good Commit Message™. Consult the [Erlang's contributing guide](https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
-if you're not sure what constitutes a Good Commit Message™. Use [interactive rebase](https://help.github.com/articles/about-git-rebase)
-to group your commits into logical units of working before making them public.
+if you're unsure of what constitutes a Good Commit Message™. Use [interactive rebase](https://help.github.com/articles/about-git-rebase)
+to group your commits into logical units of work before making it public.
 
 Note that every commit you make must be signed. By signing off your work you indicate that you
 are accepting the [Developer Certificate of Origin](https://developercertificate.org/).