Update the link to the latest OS image (#1182)

## What this patch does to fix the issue.
Update the link to the latest OS image (ubuntu 18.04).

## Link to any relevant issues or pull requests.
Closes #1169

docs/install/install.md

@@ -68,9 +68,9 @@ All example commands should work if you use Linux or macOS. If you are using a d
 ### Download Linux system image (On your PC)
 You can download an upt-to-date-for-Blueoil Linux system image by:
 
-    $ wget https://storage.googleapis.com/blueoil-asia-northeast1/os-images/de10nano_ubuntu_TCAv2.img.gz
+    $ wget https://storage.googleapis.com/blueoil-asia-northeast1/os-images/de10nano/ubuntu1804/v0.3/de10nano_ubuntu_1804.img.gz
 
-The downloaded file should contain the image "de10nano_ubuntu_TCAv2.img".
+The downloaded file should contain the image "de10nano_ubuntu_1804.img".
 Insert an empty microSD card (8GB+) into your PC and write the downloaded image to it.
 - Using Etcher [Recommended]
     - We recommend using the open source software [Etcher](https://www.balena.io/etcher/) to help you write the image on any platform.
@@ -80,7 +80,7 @@ Insert an empty microSD card (8GB+) into your PC and write the downloaded image
     - Confirm the path name of the target microSD. It should be `/dev/[your_target_name]`.
     - Type the following command:
 ```
-$ cat de10nano_ubuntu_TCAv2.img.gz | gunzip | sudo dd of=/dev/[your_target_name] bs=4M
+$ cat de10nano_ubuntu_1804.img.gz | gunzip | sudo dd of=/dev/[your_target_name] bs=4M
 ```
 
 - Using macOS terminal
@@ -89,7 +89,7 @@ $ cat de10nano_ubuntu_TCAv2.img.gz | gunzip | sudo dd of=/dev/[your_target_name]
     - To make the process faster, append an `r` in front of `[your_target_name]`.
     - Type the following command:
 ```
-$ cat de10nano_ubuntu_TCAv2.img.gz | gunzip | sudo dd of=/dev/r[your_target_name] bs=4m
+$ cat de10nano_ubuntu_1804.img.gz | gunzip | sudo dd of=/dev/r[your_target_name] bs=4m
 ```
 
 Remove the microSD from your host system after the operation have finished.
@@ -111,8 +111,8 @@ $ sudo cu -l  /dev/[your_fpga_board]  -s 115200
 Connected.
 ```
 Hit enter, and you can login using the following information:
-- User name: root
-- Password: (nothing)
+- User name: ubuntu
+- Password: ubuntu
 
 When the board is booted with the above image, around 300 MB will be available.
 But if one wants to expand the root partition to fill the whole free space available they can do this by running the following commands: