Merge branch 'docs-private-vs-personal-access-tokens' into 'master'

Docs: fix private access token -> personal access token

See merge request gitlab-org/gitlab-ce!22867

doc/topics/authentication/index.md

@@ -36,7 +36,7 @@ This page gathers all the resources for the topic **Authentication** within GitL
 ## API
 
 - [OAuth 2 Tokens](../../api/README.md#oauth-2-tokens)
-- [Private Tokens](../../api/README.md#private-tokens)
+- [Personal access tokens](../../api/README.md#personal-access-tokens)
 - [Impersonation tokens](../../api/README.md#impersonation-tokens)
 - [GitLab as an OAuth2 provider](../../api/oauth2.md#gitlab-as-an-oauth2-provider)