chore: fix spelling and grammar (#500)

Author: jbampton

CONTRIBUTING.md

@@ -44,17 +44,17 @@ or
 $ make deps
 ```
 
-You should be able to build the binaries with either the go command or the Gradle command, which is available in [README](https://github.com/apache/openwhisk-cli/blob/master/README.md).
+You should be able to build the binaries with either the go command, or the Gradle command, which is available in [README](https://github.com/apache/openwhisk-cli/blob/master/README.md).
 
 
 ## Proposing new features
 
-If you would like to implement a new feature, please [raise an issue](https://github.com/apache/openwhisk-cli/issues) before sending a pull request so the feature can be discussed.
+If you would like to implement a new feature, please [raise an issue](https://github.com/apache/openwhisk-cli/issues) before sending a pull request, so the feature can be discussed.
 This is to avoid you spending your valuable time working on a feature that the project developers are not willing to accept into the code base.
 
 ## Fixing bugs
 
-If you would like to fix a bug, please [raise an issue](https://github.com/apache/openwhisk-cli/issues) before sending a pull request so it can be discussed.
+If you would like to fix a bug, please [raise an issue](https://github.com/apache/openwhisk-cli/issues) before sending a pull request, so it can be discussed.
 If the fix is trivial or non controversial then this is not usually necessary.
 
 ## Merge approval
@@ -83,7 +83,7 @@ Use idomatic go. Document exported functions.
 
 # Publishing Tagged Release to Homebrew
 
- [Homebrew](https://brew.sh) is used to install `wsk` locally. Once we release a new version of `wsk` we should update its version in homebrew.
+ [Homebrew](https://brew.sh) is used to install `wsk` locally. Once we release a new version of `wsk` we should update its version in Homebrew.
 
  Get the new release SHA256 checksum by downloading the Source Code (tar.gz) from the [releases page](https://github.com/apache/openwhisk-cli/releases) and running `shasum -a 256 X.Y.Z.tar.gz` on the tarball.
 

README.md

@@ -30,7 +30,7 @@ OpenWhisk Command-line Interface (CLI) is a unified tool that provides a consist
 
 Here are some quick links to help you get started:
 
-- [Downloading released binaries](#downloading-released-binaries) for Linux, Mac OS and Windows
+- [Downloading released binaries](#downloading-released-binaries) for Linux, macOS and Windows
 - [Running the `wsk` CLI](#running-the-wsk-cli) executable
 - [Building the project](#building-the-project) - download and build the GoLang source code
 - [Contributing to the project](#contributing-to-the-project) - join us!
@@ -46,10 +46,10 @@ We currently provide binaries for the following Operating Systems (OS) and archi
 Operating System | Architectures
 --- | ---
 Linux | i386, AMD64, ARM, ARM64, PPC64 (Power), S/390 and IBM Z
-Mac OS (Darwin) | 386<sup>[1](#1)</sup>, AMD64
+macOS (Darwin) | 386<sup>[1](#1)</sup>, AMD64
 Windows | 386, AMD64
 
-1. Mac OS, 32-bit (386) released versions are not available for builds using Go lang version 1.15 and greater.
+1. macOS, 32-bit (386) released versions are not available for builds using Go lang version 1.15 and greater.
 
 We also provide instructions on how to build your own binaries from source code. See [Building the project](#building-the-project).
 
@@ -71,7 +71,7 @@ To get CLI command debug information, include the `-d`, or `--debug` flag when e
 
 ### GoLang setup
 
-The Openwhisk CLI is a GoLang program so you will first need to [Download and install GoLang](https://golang.org/dl/) onto your local machine.
+The Openwhisk CLI is a GoLang program, so you will first need to [Download and install GoLang](https://golang.org/dl/) onto your local machine.
 
 > **Note** Go version 1.15 or higher is recommended
 
@@ -124,7 +124,7 @@ Supported value combinations include:
 `GOOS` | `GOARCH`
 --- | ---
 linux | 386 (32-bit), amd64 (64-bit), s390x (S/390, Z), ppc64le (Power), arm (32-bit), arm64 (64-bit)
-darwin (Mac OS) | amd64
+darwin (macOS) | amd64
 windows | 386 (32-bit), amd64 (64-bit)
 
 ### Build using Gradle
@@ -319,4 +319,4 @@ go mod edit -go=1.15
 
 ## Continuous Integration
 
-Travis CI is used as a continuous delivery service for Linux and Mac. Currently Travis CI supports the environments of Linux and Mac, but it is not available for Windows. The project would like to add AppVeyor CI in the future to run test cases for Windows.
+Travis CI is used as a continuous delivery service for Linux and Mac. Currently, Travis CI supports the environments of Linux and Mac, but it is not available for Windows. The project would like to add AppVeyor CI in the future to run test cases for Windows.