Update README.md about installation MongoDB and setting.

@@ -10,7 +10,7 @@ KHU-Hub repo: [khuhub.khu.ac.kr/2018102216/dev-profile](https://khuhub.khu.ac.kr
 - [x] your basic profile
 - [x] random quotes **_for developers_** to motivate you :sparkles:
 - [x] the amount of commits you've done on [GitHub](https://github.com/) at a glance
-- [ ] your most-contributed project on GitHub
+- [x] your most-contributed project on GitHub
 - [x] today's trending repositories on GitHub
       <br>
 
@@ -41,6 +41,36 @@ npm run dev:assets
 ```
 
 <br>
+### Installation MongoDB
+    1. Access to the MongoDB homepage.
+    ![image](/uploads/3d5d283732343d4c5ff4b5c7bd16c78f/image.png)
+    
+    2. Select options and download MongoDB.
+    ![image](/uploads/46038b5c881bb18074dd8e732804f5d7/image.png)
+    
+    3. If this screen appears when installing MongoDB, please select 'complete' and proceed.
+    ![image](/uploads/510d184825d6eaf04dcb2d254f03b918/image.png)
+    
+    4. When you enter 'mongo' command in vsc terminal, it is installed well when the screen appears as below.
+    ![image](/uploads/202bf8555f6842938d15c6e3b0e789c1/image.png)
+    
+### To setting environment variable.
+    ps. When entering 'mongo' command in vsc terminal, skip this part if it runs well.
+    
+    1. Find folder where mongoDB is installed, and make a copy of the folder's route.
+    ![image](/uploads/93b13c8df931ef11781d21ad574ee441/image.png)
+    
+    2. And you open the 'environment variable' page. If using window environment, you can use command (window + R) and input 'sysdm.cpl ,3'. And click 'environment variable'.
+    ![image](/uploads/64278904603d6b3cdb78a0689695344a/image.png)
+    
+    3. You must find 'path' in 'system variable' categroy, not 'users variable'. If you find 'path' in 'system variable', then check 'path' and click 'Editing'.
+    ![image](/uploads/9077ec8854585640dfb526e45cbcb3fb/image.png)
+    
+    4. Create a new environmental variable path using the Mongo db address you copied earlier.
+    ![image](/uploads/0018e1de51ae1c10cc9a5d5bc01fcf9d/image.png)
+    
+    5. Please check if Mongo Db is working well in fourth method of "Installation MongoDB".
+
     
 ### API reference