feat: epub bookmarks (#1337)

Co-authored-by: vedi0boy <nate@origin8publishing.com>
Co-authored-by: Uri Tauber <uritaube@gmail.com>

USER_GUIDE.md

@@ -35,6 +35,7 @@ Welcome to the **CrossPoint** firmware. This guide outlines the hardware control
     - [Supported Languages](#supported-languages)
   - [5. Reader Menu](#5-reader-menu)
     - [5.1 Chapter Selection](#51-chapter-selection)
+    - [5.2. Bookmarks](#52-bookmarks)
   - [6. Current Limitations \& Roadmap](#6-current-limitations--roadmap)
   - [7. Troubleshooting Issues \& Escaping Bootloop](#7-troubleshooting-issues--escaping-bootloop)
 
@@ -502,7 +503,17 @@ Accessible by selecting **Chapters** from the Reader Menu.
 
 ---
 
-## 6. Current Limitations & Roadmap
+### 5.2 Bookmarks
+
+Bookmarks can be created to quickly save and restore your place in a book.
+
+To create a bookmark, hold **Confirm** for 1 second while inside a book. A popup will appear letting you know a bookmark was created. The popup message will automatically disappear in a couple of seconds.
+
+To open bookmarks, press **Confirm** while inside a book. Then navigate to the **Bookmarks** menu. Bookmarks can be opened by navigating to them and pressing **Confirm**, which will redirect you to that place in the book. You can delete bookmarks by holding **Confirm** for 1 second, and then pressing **Confirm** again to confirm deletion, or **Back** to cancel.
+
+Bookmarks are stored in the `.crosspoint/bookmarks` folder in the JSON format.
+
+## 7. Current Limitations & Roadmap
 
 Please note that this firmware is currently in active development. The following features are **not yet supported** but are planned for future updates:
 
@@ -514,7 +525,7 @@ Please note that this firmware is currently in active development. The following
 
 ---
 
-## 7. Troubleshooting Issues & Escaping Bootloop
+## 8. Troubleshooting Issues & Escaping Bootloop
 
 If an issue or crash is encountered while using Crosspoint, feel free to raise an issue ticket and attach the logs.