Update docker title for docker-in-docker workflow

`docker-in-docker` is a workflow not an specific executor. It uses the
[Docker executor](https://docs.gitlab.com/runner/executors/docker.html).

doc/ci/docker/using_docker_build.md

@@ -91,7 +91,7 @@ NOTE: **Note:**
 By adding `gitlab-runner` to the `docker` group you are effectively granting `gitlab-runner` full root permissions.
 For more information please read [On Docker security: `docker` group considered harmful](https://www.andreas-jung.com/contents/on-docker-security-docker-group-considered-harmful).
 
-### Use docker-in-docker executor
+### Use docker-in-docker workflow with Docker executor
 
 The second approach is to use the special docker-in-docker (dind)
 [Docker image](https://hub.docker.com/_/docker/) with all tools installed

doc/ci/docker/using_kaniko.md

@@ -11,7 +11,8 @@ Requires GitLab Runner 11.2 and above.
 container images from a Dockerfile, inside a container or Kubernetes cluster.
 
 kaniko solves two problems with using the
-[docker-in-docker build](using_docker_build.md#use-docker-in-docker-executor) method:
+[docker-in-docker
+build](using_docker_build.md#use-docker-in-docker-workflow-with-docker-executor) method:
 
 - Docker-in-docker requires [privileged mode](https://docs.docker.com/engine/reference/run/#runtime-privilege-and-linux-capabilities)
   in order to function, which is a significant security concern.

doc/ci/examples/browser_performance.md

@@ -15,7 +15,7 @@ your code by using GitLab CI/CD and [sitespeed.io](https://www.sitespeed.io)
 using Docker-in-Docker.
 
 First, you need GitLab Runner with
-[docker-in-docker executor](../docker/using_docker_build.md#use-docker-in-docker-executor).
+[docker-in-docker build](../docker/using_docker_build.md#use-docker-in-docker-workflow-with-docker-executor).
 
 Once you set up the Runner, add a new job to `.gitlab-ci.yml` that
 generates the expected report:

doc/ci/examples/code_quality.md

@@ -14,7 +14,7 @@ This example shows how to run Code Quality on your code by using GitLab CI/CD
 and Docker.
 
 First, you need GitLab Runner with
-[docker-in-docker executor](../docker/using_docker_build.md#use-docker-in-docker-executor).
+[docker-in-docker executor](../docker/using_docker_build.md#use-docker-in-docker-workflow-with-docker-executor).
 
 Once you set up the Runner, include the CodeQuality template in your CI config: