Fix whitespace in ci docs

Many code blocks are 4spaced, and they render in GitLab
without coloring as a result, even though they are
fenced with a language label. If in a list, other items
will render as being in a code block too, even if not
meant to. This fixes all these issues for most docs in
/ci, and cleans up other minor whitespace issues too.

doc/ci/docker/using_docker_images.md

@@ -526,6 +526,7 @@ it's provided as an environment variable. This is because GitLab Runnner uses **
 runtime.
 
 ### Using statically-defined credentials
+
 There are two approaches that you can take in order to access a
 private registry. Both require setting the environment variable
 `DOCKER_AUTH_CONFIG` with appropriate authentication info.
@@ -662,6 +663,7 @@ To configure credentials store, follow these steps:
    Make sure helper program is available in GitLab Runner `$PATH`.
 
 1. Make GitLab Runner use it. There are two ways to accomplish this. Either:
+
    - Create a
      [variable](../variables/README.md#gitlab-cicd-environment-variables)
      `DOCKER_AUTH_CONFIG` with the content of the
@@ -693,6 +695,7 @@ To configure access for `aws_account_id.dkr.ecr.region.amazonaws.com`, follow th
 1. Make sure `docker-credential-ecr-login` is available in GitLab Runner's `$PATH`.
 
 1. Make GitLab Runner use it. There are two ways to accomplish this. Either:
+
    - Create a [variable](../variables/README.md#gitlab-cicd-environment-variables)
      `DOCKER_AUTH_CONFIG` with the content of the
      Docker configuration file as the value:

doc/ci/examples/artifactory_and_gitlab/index.md

@@ -42,6 +42,7 @@ project:
    ```
    https://gitlab.com/gitlab-examples/maven/simple-maven-dep.git
    ```
+
 1. Click **Create project**
 
 This application is nothing more than a basic class with a stub for a JUnit based test suite.
@@ -190,6 +191,7 @@ We'll use again a Maven app that can be cloned from our example project:
    ```
    https://gitlab.com/gitlab-examples/maven/simple-maven-app.git
    ```
+
 1. Click **Create project**
 
 This one is a simple app as well. If you look at the `src/main/java/com/example/app/App.java`

doc/ci/examples/test_phoenix_app_with_gitlab_ci_cd/index.md

@@ -204,12 +204,11 @@ when running our Phoenix in our `localhost`.
 - Create an empty file named `.gitkeep` into `hello_gitlab_ci/priv/repo/migrations`
 
   As our project is still fresh, we don't have any data on our database, so, the `migrations`
-directory will be empty.
+  directory will be empty.
   Without `.gitkeep`, git will not upload this empty directory and we'll got an error when running our
-test on GitLab.
+  test on GitLab.
 
-    > **Note:**
-    If we add a folder via the GitLab UI, GitLab itself will add the `.gitkeep` to that new dir.
+  > **Note:** If we add a folder via the GitLab UI, GitLab itself will add the `.gitkeep` to that new dir.
 
 Now, let's run a local test and see if everything we did didn't break anything.