docs: restructure documentation

This rewrite follows the principles of https://diataxis.fr/

Co-authored-by: Erik Michelson <github@erik.michelson.eu>
Signed-off-by: Philip Molares <philip.molares@udo.edu>
Signed-off-by: Erik Michelson <github@erik.michelson.eu>

docs/content/tutorials/user.md

@@ -0,0 +1,41 @@
+# Create a user
+
+This tutorial assumes that you just deployed a HedgeDoc instance with [this guide][setup].
+We'll assume the domain you use for the instance is <https://md.example.com>, so please
+substitute your actual domain anywhere you encounter <https://md.example.com>
+
+1. Go to <https://md.example.com>.
+
+2. Click the "Sign In" button in the top right corner of the page.
+
+   ![Sign In button on the HedgeDoc start page][sign-in]{ width="400" }
+
+3. Click on the "Register" button in "Sign in via Username" section.
+
+   ![Register button in Sign in via Username section][register-button]{ width="500" }
+
+4. Fill out the form.
+
+   You are able to change any of these values except the username, so please chose a username
+   you want to keep.
+   ![Register form][register-form]{ width="500" }
+
+5. Click on the "Register" button.
+
+Congratulation you know have a working local user account for your HedgeDoc instance.
+
+## Further reading
+
+- [Creating your first note][tutorials/first-note]
+- [Creating your first presentation][tutorials/first-presentation]
+- [Advanced configuration options][config]
+
+[setup]: ./setup.md
+
+[sign-in]: ../images/tutorial/top-right.png
+[register-button]: ../images/tutorial/user/register-button.png
+[register-form]: ../images/tutorial/user/register-form.png
+
+[tutorials/first-note]: /tutorials/first-note/
+[tutorials/first-presentation]: /tutorials/first-presentation/
+[config]: /references/config/