Merge branch 'patch-1' into 'master'

Fixed Typo in README.md

## What does this MR do?
Found a Typo in the README.md file.  before_script should be with ":"  Script didn't work for me without ":"

## Why was this MR needed?
Missing ":" can be irritating for new users.

See merge request !4419

doc/ci/yaml/README.md

@@ -811,7 +811,7 @@ deploy:
 It's possible to overwrite globally defined `before_script` and `after_script`:
 
 ```yaml
-before_script
+before_script:
 - global before script
 
 job: