Improve markdown and fix links that don't render correctly

doc/install/digitaloceandocker.md

 # Digital Ocean and Docker Machine test environment
 
-## Warning. This guide is for quickly testing different versions of GitLab and
-## not recommended for ease of future upgrades or keeping the data you create.
+CAUTION: **Caution:**
+This guide is for quickly testing different versions of GitLab and not recommended for ease of
+future upgrades or keeping the data you create.
 
 ## Initial setup
 
@@ -12,84 +13,79 @@ locally on either macOS or Linux.
 
 #### Install Docker Toolbox
 
-1. [https://www.docker.com/products/docker-toolbox](https://www.docker.com/products/docker-toolbox)
+- <https://www.docker.com/products/docker-toolbox>
 
 ### On Linux
 
 #### Install Docker Engine
 
-1. [https://docs.docker.com/engine/installation/linux](https://docs.docker.com/engine/installation/linux/)
+- <https://docs.docker.com/engine/installation/linux/>
 
 #### Install Docker Machine
 
-1. [https://docs.docker.com/machine/install-machine](https://docs.docker.com/machine/install-machine/)
+- <https://docs.docker.com/machine/install-machine/>
 
-_The rest of the steps are identical for macOS and Linux_
+NOTE: **Note:**
+The rest of the steps are identical for macOS and Linux.
 
 ### Create new docker host
 
-1. Login to Digital Ocean
-1. Generate a new API token at https://cloud.digitalocean.com/settings/api/tokens
+1. Login to Digital Ocean.
+1. Generate a new API token at <https://cloud.digitalocean.com/settings/api/tokens>.
 
+    This command will create a new DO droplet called `gitlab-test-env-do` that will act as a docker host.
 
-This command will create a new DO droplet called `gitlab-test-env-do` that will act as a docker host.
+    NOTE: **Note:**
+    4GB is the minimum requirement for a Docker host that will run more than one GitLab instance.
 
-**Note: 4GB is the minimum requirement for a Docker host that will run more then one GitLab instance**
+    - RAM: 4GB
+    - Name: `gitlab-test-env-do`
+    - Driver: `digitalocean`
 
-+ RAM: 4GB
-+ Name: `gitlab-test-env-do`
-+ Driver: `digitalocean`
+1. Set the DO token:
 
+    ```sh
+    export DOTOKEN=<your generated token>
+    ```
 
-**Set the DO token** - Replace the string below with your generated token
+1. Create the machine:
 
-```
-export DOTOKEN=cf3dfd0662933203005c4a73396214b7879d70aabc6352573fe178d340a80248
-```
-
-**Create the machine**
-
-```
-docker-machine create \
+    ```sh
+    docker-machine create \
       --driver digitalocean \
       --digitalocean-access-token=$DOTOKEN \
       --digitalocean-size "4gb" \
         gitlab-test-env-do
-```
-
-+ Resource: https://docs.docker.com/machine/drivers/digital-ocean/
+    ```
 
+Resource: <https://docs.docker.com/machine/drivers/digital-ocean/>.
 
 ### Creating GitLab test instance
 
-
 #### Connect your shell to the new machine
 
-
 In this example we'll create a GitLab EE 8.10.8 instance.
 
-
 First connect the docker client to the docker host you created previously.
 
-```
+```sh
 eval "$(docker-machine env gitlab-test-env-do)"
 ```
 
 You can add this to your `~/.bash_profile` file to ensure the `docker` client uses the `gitlab-test-env-do` docker host
 
-
 #### Create new GitLab container
 
-+ HTTP port: `8888`
-+ SSH port: `2222`
-   + Set `gitlab_shell_ssh_port` using `--env GITLAB_OMNIBUS_CONFIG `
-+ Hostname: IP of docker host
-+ Container name: `gitlab-test-8.10`
-+ GitLab version: **EE** `8.10.8-ee.0`
+- HTTP port: `8888`
+- SSH port: `2222`
+  - Set `gitlab_shell_ssh_port` using `--env GITLAB_OMNIBUS_CONFIG`
+- Hostname: IP of docker host
+- Container name: `gitlab-test-8.10`
+- GitLab version: **EE** `8.10.8-ee.0`
 
 ##### Set up container settings
 
-```
+```sh
 export SSH_PORT=2222
 export HTTP_PORT=8888
 export VERSION=8.10.8-ee.0
@@ -97,7 +93,8 @@ export NAME=gitlab-test-8.10
 ```
 
 ##### Create container
-```
+
+```sh
 docker run --detach \
 --env GITLAB_OMNIBUS_CONFIG="external_url 'http://$(docker-machine ip gitlab-test-env-do):$HTTP_PORT'; gitlab_rails['gitlab_shell_ssh_port'] = $SSH_PORT;" \
 --hostname $(docker-machine ip gitlab-test-env-do) \
@@ -110,23 +107,20 @@ gitlab/gitlab-ee:$VERSION
 
 ##### Retrieve the docker host IP
 
-```
+```sh
 docker-machine ip gitlab-test-env-do
 # example output: 192.168.151.134
 ```
 
-
-+ Browse to: http://192.168.151.134:8888/
-
+Browse to: <http://192.168.151.134:8888/>.
 
 ##### Execute interactive shell/edit configuration
 
-
-```
+```sh
 docker exec -it $NAME /bin/bash
 ```
 
-```
+```sh
 # example commands
 root@192:/# vi /etc/gitlab/gitlab.rb
 root@192:/# gitlab-ctl reconfigure
@@ -134,6 +128,6 @@ root@192:/# gitlab-ctl reconfigure
 
 #### Resources
 
-+ [https://docs.gitlab.com/omnibus/docker/](https://docs.gitlab.com/omnibus/docker/)
-+ [https://docs.docker.com/machine/get-started/](https://docs.docker.com/machine/get-started/)
-+ [https://docs.docker.com/machine/reference/ip/](https://docs.docker.com/machine/reference/ip/)+
+- <https://docs.gitlab.com/omnibus/docker/>.
+- <https://docs.docker.com/machine/get-started/>.
+- <https://docs.docker.com/machine/reference/ip/>.