adds readme section about how to set up ci

README.md

 Change to Document Title Here
 =============================
 
+Continuous Integration
+----------------------
+
+In GitLab, projects can **automatically be built, tested and deployed**. In
+general, this is called **continuous integration** (CI) and **continuous
+deployment** (CD). Both together are abbreviated to **CI / CD** and this is
+what you will see in the GitLab web interface.
+
+You define what the CI server should do in the `.gitlab-ci.yml` file. This
+project template contains two stages:
+
+1.  **check** to run the spell checker on all document sources
+1.  **deploy** to upload the built document to an iDiv [Nextcloud][idiv-nc]
+    share
+
+### Spell Checking
+
+Unfortunately, spell checking is still [a bit awkward][spell-check-issue]. The
+problem is that the currently existing spell checking tools are not really well
+integrated. See [this issue][spell-check-issue] for more information and
+progress.
+
+If you think that the spell checker with its [current
+limitations][spell-check-issue] is more of an annoyance than help, you can
+disable it by removing the **check** stage from the `.gitlab-ci.yml` file. Once
+the issues are fixed, you can simply re-enable it by reverting the commit.
+
+### Deployment to Nextcloud
+
+The **deploy** stage tries to upload the built document to an iDiv
+[Nextcloud][idiv-nc] share. To make this work, you will need to set this up
+first by following these steps:
+
+1.  **log in to Nextcloud**
+
+    Go to the iDiv [Nextcloud][idiv-nc] and log in.
+
+1.  **create a new, empty folder**
+
+    My recommendation is to create a top-level folder named **documents**.
+    Then, create a sub-folder named after your project, e.g. the document
+    title.
+
+    Avoid spaces and use dashes or underscores instead!
+
+1.  **share the folder**
+
+    Click on the **share** icon of the folder. Click on the plus `+` icon next
+    to **Share link**. Check the **Password protect** box and set your
+    password. Then click the **Allow upload and editing** radio button.
+
+    Finally, click on the **copy link to clipboard** icon.
+
+1.  **CI settings**
+
+    Go to your GitLab project. Go to **Settings**, **CI / CD** and expand the
+    **Variables** section. Add two variables:
+
+    1.  `NEXTCLOUD_SHARE`, paste the share link you copied from Nextcloud.
+        Remove everything except the part after the last slash `/`, e.g. if
+        your link is:
+
+        ```
+        https://portal.idiv.de/nextcloud/index.php/s/aFgeXn5Ay9qffbd
+        ```
+
+        ... you only need the `aFgeXn5Ay9qffbd` part.
+
+    1.  `NEXTCLOUD_PW`, with the password of the share.
+
+    Make sure both variables are masked so the values will not show up in your
+    logs.
+
 Building
 --------
 
@@ -33,6 +106,9 @@ build the template PDF, you need these dependencies:
 **Note:** On MS Windows, it might be helpful using [chocolatey][].
 
 
+[idiv-nc]: https://portal.idiv.de/nextcloud/
+[spell-check-issue]: https://git.idiv.de/templates/pandoc/issues/3
+
 [chocolatey]: https://chocolatey.org/
 [git]: https://git-scm.com/downloads
 [graphviz]: https://graphviz.gitlab.io/download/