doc: update tagline in README (#269)

Author: Quentin Brosse

CONTRIBUTING.md

@@ -59,7 +59,7 @@ To submit code:
 - Push your commit(s) to your topic branch on your fork
 - Open a pull request against `scaleway-sdk-go` master branch that follows [PR guidelines](#pull-request-guidelines)
 
-The maintainers of `scaleway-sdk-go` use a "Let's Get This Merged" (LGTM) message in the pull request to note that the commits are ready to merge.
+The [maintainers](MAINTAINERS.md) of `scaleway-sdk-go` use a "Let's Get This Merged" (LGTM) message in the pull request to note that the commits are ready to merge.
 After one or more maintainer states LGTM, we will merge.
 If you have questions or comments on your code, feel free to correct these in your branch through new commits.
 

README.md

@@ -12,8 +12,7 @@
 **:warning: This is an early release, keep in mind that the API can break**
 
 
-Scaleway is a simple way to build, deploy and scale your infrastructure in the cloud.
-We help thousands of developers and businesses to run their infrastructures without any issue.
+Scaleway is a single way to create, deploy and scale your infrastructure in the cloud. We help thousands of businesses to run their infrastructures easily.
 
 ## Documentation