Add upgrade guide

docs/v0.7.0-upgrade.md

@@ -0,0 +1,57 @@
+## Upgrading to v0.7.0 from previous versions
+
+In essence, the `glance.yml` file has been moved from the root of the project to a `config/` directory and you now need to mount that directory to `/app/config` in the container.
+
+### Before
+
+Versions before v0.7.0 used a `docker-compose.yml` that looked like the following:
+
+```yaml
+services:
+  glance:
+    image: glanceapp/glance
+    volumes:
+      - ./glance.yml:/app/glance.yml
+    ports:
+      - 8080:8080
+```
+
+And expected you to have the following directory structure:
+
+```plaintext
+glance/
+    docker-compose.yml
+    glance.yml
+```
+
+### After
+
+With the release of v0.7.0, the recommended `docker-compose.yml` looks like the following:
+
+```yaml
+services:
+  glance:
+    container_name: glance
+    image: glanceapp/glance
+    volumes:
+      - ./config:/app/config
+    ports:
+      - 8080:8080
+```
+
+And expects you to have the following directory structure:
+
+```plaintext
+glance/
+    docker-compose.yml
+    config/
+        glance.yml
+```
+
+## Why this change was necessary
+
+1. Mounting a file rather than a directory is not common practice and leads to some issues, such as creating a directory if the file is not present, which has tripped up multiple people and caused unnecessary confusion
+2. v0.7.0 added automatic reloads when the configuration file changes, which based on testing didn't work when mounting a single file
+3. v0.7.0 added the ability to include config files, so you'd have to make this change anyways if you wanted to take advantage of that feature
+
+Taking all of these into account, it felt like the right time to implement the change.