Docs: Fix the way tabs are declared

Since python doesn't have a way to lock deps for a particlar project
by default, I didn't bother with it. This resulted in mkdocs updating at
some point, bringing a breaking change to how tabs are declared and
broken tabs on docs-develop.pleroma.social. I've learned my lesson
and locked deps with pipenv in pleroma/docs!5. This MR updates Pleroma
docs to use the new tab style, fortunately my editor did most of it.

Closes #2045

docs/administration/CLI_tasks/oauth_app.md

@@ -7,10 +7,14 @@
 Optional params:
   * `-s SCOPES` - scopes for app, e.g. `read,write,follow,push`.
 
-```sh tab="OTP"
- ./bin/pleroma_ctl app create -n APP_NAME -r REDIRECT_URI
-```
+=== "OTP"
 
-```sh tab="From Source"
-mix pleroma.app create -n APP_NAME -r REDIRECT_URI
-```
+    ```sh
+     ./bin/pleroma_ctl app create -n APP_NAME -r REDIRECT_URI
+    ```
+
+=== "From Source"
+
+    ```sh
+    mix pleroma.app create -n APP_NAME -r REDIRECT_URI
+    ```