Initial commit

Signed-off-by: mikesir87 <mikesir87@gmail.com>

Imported from dockersamples/101-tutorial, removed other languages
for now, and replaced PWD references with Docker Desktop.

docs/tutorial/index.md

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+---
+next_page: app.md
+---
+
+## The command you just ran
+
+Congratulations! You have started the container for this tutorial!
+Let's first explain the command that you just ran. In case you forgot,
+here's the command:
+
+```cli
+docker run -d -p 80:80 docker/getting-started
+```
+
+You'll notice a few flags being used. Here's some more info on them:
+
+- `-d` - run the container in detached mode (in the background)
+- `-p 80:80` - map port 80 of the host to port 80 in the container
+- `docker/getting-started` - the image to use
+
+!!! info "Pro tip"
+    You can combine single character flags to shorten the full command.
+    As an example, the command above could be written as:
+    ```
+    docker run -dp 80:80 docker/getting-started
+    ```
+
+## The Docker Dashboard
+
+Before going too far, we want to highlight the Docker Dashboard, which gives
+you a quick view of the containers running on your machine. It gives you quick
+access to container logs, lets you get a shell inside the container, and lets you
+easily manage container lifecycle (stop, remove, etc.). 
+
+To access the dashboard, follow the instructions for either 
+[Mac](https://docs.docker.com/docker-for-mac/dashboard/) or 
+[Windows](https://docs.docker.com/docker-for-windows/dashboard/). If you open the dashboard
+now, you will see this tutorial running! The container name (`jolly_bouman` below) is a
+randomly created name. So, you'll most likely have a different name.
+
+![Tutorial container running in Docker Dashboard](tutorial-in-dashboard.png)
+
+
+## What is a container?
+
+Now that you've run a container, what _is_ a container? Simply put, a container is
+simply another process on your machine that has been isolated from all other processes
+on the host machine. That isolation leverages [kernel namespaces and cgroups](https://medium.com/@saschagrunert/demystifying-containers-part-i-kernel-space-2c53d6979504), features that have been 
+in Linux for a long time. Docker has worked to make these capabilities approachable and easy to use.
+
+!!! info "Creating Containers from Scratch"
+    If you'd like to see how containers are built from scratch, Liz Rice from Aqua Security
+    has a fantastic talk in which she creates a container from scratch in Go. While she makes
+    a simple container, this talk doesn't go into networking, using images for the filesystem, 
+    and more. But, it gives a _fantastic_ deep dive into how things are working.
+
+    <iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/8fi7uSYlOdc" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+
+## What is a container image?
+
+When running a container, it uses an isolated filesystem. This custom filesystem is provided 
+by a **container image**. Since the image contains the container's filesystem, it must contain everything 
+needed to run an application - all dependencies, configuration, scripts, binaries, etc. The 
+image also contains other configuration for the container, such as environment variables,
+a default command to run, and other metadata.
+
+We'll dive deeper into images later on, covering topics such as layering, best practices, and more.
+
+!!! info
+    If you're familiar with `chroot`, think of a container as extended version of `chroot`. The
+    filesystem is simply coming from the image. But, a container adds additional isolation not
+    available when simply using chroot.
+