Merge pull request #6 from djc/readme

Improve the README a little

Author: hrvolapeter

README.md

@@ -10,54 +10,60 @@
 [mit-badge]: https://img.shields.io/badge/license-MIT-blue.svg
 [mit-url]: LICENSE
 
-GCP Auth is a simple, minimal authentication library for Google Cloud Platform (GCP) providing authentication using
-services accounts that are used to issues Bearer tokens that can be used to authenticate against GCP services.
+GCP Auth is a simple, minimal authentication library for Google Cloud Platform (GCP)
+providing authentication using services accounts. Once authenticated, the service
+account can be used to acquire bearer tokens for use in authenticating against GCP
+services.
 
 Library implements two authenticatiom methods:
 
 1. Default service accounts - can be used inside GCP
-2. Custom service account - provided using environenment variable
-3. Local user authetincation - for development purposes only, using `gcloud auth` application
+2. Custom service account - provided using an environment variable
+3. Local user authentication - for development purposes only, using `gcloud auth` application
 
-Tokens should not be cached in the application and before every use a new token should be request. The GCP auth library decides
-if there is available token with appropriate scope or if a new token should be generated.
+Tokens should not be cached in the application; before every use a new token should
+be requested. The GCP auth library contains logic to determine if an already
+available token can be used, or if a new token should be requested.
 
-## Default Service Account
+## Default service account
 
-When running inside GCP the library can be asked directly without any further configuration to provide a Bearer token
-for the current service account of the service.
+When running inside GCP the library can be asked without any further configuration to
+provide a bearer token for the current service account of the service.
 
 ```rust
 let authentication_manager = gcp_auth::init().await?;
 let token = authentication_manager.get_token().await?;
 ```
 
-## Custom Service Account
+## Custom service account
 
-When running outside of GCP e.g on development laptop to allow finer granularity for permission a
-custom service account can be used. To use a custom service account a configuration file containing key
-has to be downloaded in IAM service for the service account you intend to use. The configuration file has to
-be available to the application at run time. The path to the configuration file is specified by 
+When running outside of GCP (for example, on a developer's laptop), a custom service
+account may be used to grant some permissions. To use a custom service account a
+configuration file containing a private key can be downloaded in IAM service for the
+service account you intend to use. The configuration file has to be available to the
+application at run time. The path to the configuration file is specified by the
 `GOOGLE_APPLICATION_CREDENTIALS` environment variable.
 
 ```rust
-// GOOGLE_APPLICATION_CREDENTIALS environtment variable is set-up
+// With the GOOGLE_APPLICATION_CREDENTIALS environment variable set
 let authentication_manager = gcp_auth::init().await?;
 let token = authentication_manager.get_token().await?;
 ```
 
 ## Local user authentication
-This authentication method allows developers to authenticate again GCP ices when developign locally.
-The method is intended only for development. Credentials can be set-up g `gcloud auth` utility.
-Credentials are read from file `~/.config/gcloud/ication_default_credentials.json`.
+
+This authentication method allows developers to authenticate again GCP when
+developing locally. Its use should be limited to development. Credentials can be
+set up using the `gcloud auth` utility. Credentials are read from file `~/.config/gcloud/ication_default_credentials.json`.
 
 ## FAQ
 
-### Does library support windows?
+### Does the library support windows?
 
-No
+No.
 
 # License
-Parts of implementatino have been sourced from [yup-oauth2](https://github.com/dermesser/yup-oauth2)
 
-Licensed under [MIT license](http://opensource.org/licenses/MIT).
+Parts of the implementatino have been sourced from [yup-oauth2](https://github.com/dermesser/yup-oauth2).
+
+Licensed under [MIT license](http://opensource.org/licenses/MIT).