feat: add images to the core features description

docs/contribute/specification/index.md

@@ -17,15 +17,21 @@ sidebar_position: 2
       4. 100/200/300?
    3. Sorting
    4. Link to ICU Faculty Info
-2. **Save, Sync & View the Registration:** Enrolled courses save & view feature via online database
+2. (**Save, Sync & View the Registration:** Enrolled courses save & view feature via online database)
+   - should we actually prepare online database? perhaps we can just continue to use LocalStorage like [NUSMods](https://nusmods.com/)
    1. Calculate the sum of units
    2. Can compare multiple courses
 
 ### Second Priority
 
-1. **Course Recommendation**: Course recommendation system based on the user data with privacy security
+1. ~~**Course Recommendation**: Course recommendation system based on the user data with privacy security~~
+   - this feature might be unnecessary cuz the comment feature or TES feature might make course comparisons easy
 2. **Integrated curriculum tree**: (pre-required course list, interactive curriculum tree)
+   - Good example in [NUSMods](https://nusmods.com/)
+     ![NUSMods "Prerequisite Tree"](nusmods-prerequisite-tree.png)
 3. **Bucket List**: Save the courses u wanna take next year
+   - Good example in [NUSMods](https://nusmods.com/)
+     ![nusmods-course-planner](nusmods-course-planner.png)
 4. **Requirement Checker**: Check Graduation/Major Requirements based on already enrolled courses list
 5. **I'm feeling lucky**: show random courses to get serendipity
    1. Search for random academic keywords (e.g. "Stereochemistry", "Chomsky")
@@ -34,7 +40,10 @@ sidebar_position: 2
 7. **Comment for Courses (?)**: User Review of the Syllabus
 8. **Import Required Courses**: ELA, 教職, 学芸員 (selecting feature of the courses from the 選択必修)
 9. **Export to Google Calendar**
-10. [We will receive ideas for additional features via ましゅまろ or other social media from all the ICU students!! (after releasing v1.0.0)]
+
+- we can (perhaps easily) implement this by setting Date strings to timetable data
+
+11. [We will receive ideas for additional features via ましゅまろ or other social media, Google Form, GitHub from all the ICU students!! (after releasing v1.0.0)]
 
 ## Routing
 
@@ -51,5 +60,5 @@ sidebar_position: 2
 
 ### Docs
 
-- https://docs.catalogue.icu
+- https://docs.catalogue.icu (this site)
 - repo: https://github.com/ItsukiKigoshi/icu-catalogue-docs