creating trusted app from adminFE & mix task

docs/administration/CLI_tasks/oauth_app.md

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+# Creating trusted OAuth App
+
+{! backend/administration/CLI_tasks/general_cli_task_info.include !}
+
+## Create trusted OAuth App.
+
+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
+```
+
+```sh tab="From Source"
+mix pleroma.app create -n APP_NAME -r REDIRECT_URI
+```