Slight modification of UG, DG, and upload team members' photos

docs/AboutUs.md

@@ -3,20 +3,21 @@
 
 Display | Name  |            Github Profile            | Portfolio 
 --------|:-----:|:------------------------------------:|:---------:
-![](//docs/team/Khanh.jpg) | Khanh | [Github](https://github.com/tkhahns) | [Portfolio](./team/tkhahns.md)
+![](./team/Khanh.jpg) | Khanh | [Github](https://github.com/tkhahns) | [Portfolio](./team/tkhahns.md)
 
 Display |   Name   |             Github Profile             | Portfolio 
 --------|:--------:|:--------------------------------------:|:---------:
-![](//docs/team/Rex.png) | Rex Koh  | [Github](https://github.com/rexkoh425) | [Portfolio](./team/rexkoh425.md)
+![](./team/Rex.png) | Rex Koh  | [Github](https://github.com/rexkoh425) | [Portfolio](./team/rexkoh425.md)
 
 Display | Name | Github Profile | Portfolio 
 --------|:----:|:--------------:|:---------:
-![](//docs/team/Ryan.jpg) | Ryan Fong | [Github](https://github.com/CT9ARyan) | [Portfolio](./team/ct9aryan.md)
+
+![](./team/Ryan.jpeg) | Ryan Fong | [Github](https://github.com/CT9ARyan) | [Portfolio](./team/ct9aryan.md)
 
 Display |  Name   |             Github Profile             | Portfolio 
 --------|:-------:|:--------------------------------------:|:---------:
-![](//docs/team/Aaron.jpg) | Liu Hao | [Github](https://github.com/AaronZZ10) | [Portfolio](./team/aaronzz10.md)
+![](./team/Aaron.jpg) | Liu Hao | [Github](https://github.com/AaronZZ10) | [Portfolio](./team/aaronzz10.md)
 
 Display |    Name     |             Github Profile             | Portfolio 
 --------|:-----------:|:--------------------------------------:|:---------:
-![](//docs/team/) | Kenneth Tan | [Github](https://github.com/SemiColonKen) | [Portfolio](./team/SemiColonKen.md)
+![](./team/Kenneth.jpg) | Kenneth Tan | [Github](https://github.com/SemiColonKen) | [Portfolio](./team/SemiColonKen.md)

docs/DeveloperGuide.md

@@ -318,7 +318,7 @@ transactionData.txt should be created in the data folder as well if it does not
 
 `Test case 3` :
 
-`details` : Adding a user using `add-user /u john /a 16 /c 87777777` <br>
+`details` : Adding a user using `add-user /u bill /a 16 /c 87777777` <br>
 `check` : The command should return an error message saying that the age is illegal to drive which is true 
 for most countries at age of 16. Our legal age is 18 thus changing the age to 18 and above but maximally 100 years old 
 will work now.

docs/UserGuide.md

@@ -306,6 +306,7 @@ The status will be updated automatically when a transaction record is:
 Adds a new rental transaction to the system.
 
 To add transaction bearing either an existing license plate number and/or customer name, all previous transactions containing either both or one of the parameter must be either marked as completed or be removed from the transaction list.
+It means that when a customer and a car are in a transaction, either that customer or that car cannot involve in other transactions, including transactions with different time periods (start date - end date), unless that transaction is marked as completed or be removed from the transaction list.
 
 **Format:** `add-tx /c [LICENSE_PLATE_NUMBER] /u [CUSTOMER_NAME] /d [DURATION] /s [START_DATE: dd-MM-yyyy]`
 
@@ -496,7 +497,8 @@ The transactions are displayed in the same format as list-txs.
 **Format:** `find-txs-by-customer /u [CUSTOMER_NAME]`
 
 - `/u` identifier specifies the Customer Name.
-- `CUSTOMER_NAME` must match an existing customer in the customer list. This is not case-sensitive, 'john' and 'John' is the same.
+
+- `CUSTOMER_NAME` must partially match an existing customer in the customer list. This is not case-sensitive, 'john' and 'John' is the same, and 'john' input can search for the user 'John Doe', which contains 'John'.
 
 **Example:**  
 `find-txs-by-customer /u John`