docs: setup proper documentation, organize & clean README

docs/BANNER.md

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+# Banner
+
+All notes on the internal workings of the Banner system by Ellucian.
+
+## Sessions
+
+All notes on the internal workings of Sessions in the Banner system.
+
+- Sessions are generated on demand with a random string of characters.
+  - The format `{5 random characters}{milliseconds since epoch}`
+  - Example: ``
+- Sessions are invalidated after 30 minutes, but may change.
+  - This delay can be found in the original HTML returned, find `meta[name="maxInactiveInterval"]` and read the `content` attribute.
+  - This is read at runtime (in the browser, by javascript) on initialization.
+- Multiple timers exist, one is for the Inactivity Timer.
+  - A dialog will appear asking the user to continue their session.
+  - If they click the button, the session will be extended via the keepAliveURL (see `meta[name="keepAliveURL"]`).
+  - The `keepAliveURL` does not seem to care whether the session is or was ever valid, it will always return a 200 OK with `I am Alive` as the content.
+- When searching with an invalid session (or none at all, as the case may be), the server will return 200 OK, but with an empty result response structure.
+
+```json
+{
+  "success": true,
+  "totalCount": 0,
+  "data": null, // always an array, even if empty
+  "pageOffset": 0, //
+  "pageMaxSize": 10,
+  "sectionsFetchedCount": 0,
+  "pathMode": "registration", // normally "search"
+  "searchResultsConfigs": null, // normally an array
+  "ztcEncodedImage": null // normally a static string in base64
+}
+```
+
+- This is only the handling for the search endpoint, more research is required to see how other endpoints handle invalid/expired sessions.
+- TODO: How is `pathMode` affected by an expired session, rather than an invalid/non-existent one?