Linked the documentation with the error displayed in Travis for easier u...

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | [Linked the documentation with the error displayed in Travis for easier understading during firsts contributions]
| License       | MIT
| Doc PR        | 

the sentence is incomplete