docs: add privacy policy

PRIVACY.md

@@ -0,0 +1,17 @@
+# Privacy Policy
+
+Komga is a self-hosted application. It does not transmit any data outside the machine hosting it.
+
+## Data collected
+
+Data collected is stored in the local SQLite database required for the application to function, and never leaves your
+machine.
+
+### Information provided by the user(s)
+
+- **Email address**: required to create an account
+
+### Information collected automatically
+
+- **IP address and User-Agent of authentication connections**: stored in the local database during authentication
+  attempts. That information is automatically deleted after one month.