Update README.md with correct username

[AndrewGable]

Fixes git error in install instructions

andrew ➜ ~ git clone https://github.com/hugobourget/octowatch.git
Cloning into 'octowatch'...
ERROR: Repository not found.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

andrew ➜ ~ git clone https://github.com/hbourget/octowatch.git
Cloning into 'octowatch'...
remote: Enumerating objects: 142, done.
remote: Counting objects: 100% (142/142), done.
remote: Compressing objects: 100% (81/81), done.
remote: Total 142 (delta 67), reused 114 (delta 39), pack-reused 0 (from 0)
Receiving objects: 100% (142/142), 1.55 MiB | 3.53 MiB/s, done.
Resolving deltas: 100% (67/67), done.