resources: Fix the README file of riscv-ubuntu

- The title should be riscv-ubuntu instead of x86-ubuntu.
- Fixed the file structure.

Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Change-Id: Ic84317a56ff9735f7d57117242387488f35d651c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-resources/+/58549
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: Jason Lowe-Power <power.jg@gmail.com>
diff --git a/src/riscv-ubuntu/README.md b/src/riscv-ubuntu/README.md
index e49d44e..6c38d65 100644
--- a/src/riscv-ubuntu/README.md
+++ b/src/riscv-ubuntu/README.md
@@ -1,5 +1,5 @@
 ---
-title: Linux x86-ubuntu image
+title: Linux riscv-ubuntu image
 tags:
     - riscv
     - fullsystem
@@ -37,10 +37,7 @@
   |             |___ gem5_init.sh              # The script to be appended to .bashrc on the disk image
   |             |___ post-installation.sh      # The script manipulating the disk image
   |             |___ riscv-ubuntu.json         # The Packer script
-  |      
-  |                 
   |
-  |___ ubuntu.img                              # The disk image
   |
   |___ README.md                               # This README file
 ```