Remove dead link from README.md

[Qu4tro]

git-app-manager - install "unhosted" websites locally by git cloning them

The link for the git-app-manager on the README looks dead.

I think this is the matching link: https://git-app-manager.now.sh/ .
It was posted here #97 (comment) by @wmhilton

[karma-pr-reporter]

Test Results for 37265cf:

Browser	Pass	Skip	Fail	Time	Disconnect?
Chrome 79.0.3945 (Windows 10 0.0.0)	363	0	0	3m:21s	false
Chrome Mobile 80.0.3987 (Android 0.0.0)	363	0	0	3m:43s	false
Firefox 76.0.0 (Ubuntu 0.0.0)	363	0	0	1m:5s	false
HeadlessChrome 0.0.0 (Linux 0.0.0)	363	0	0	0m:42s	false
Mobile Safari 13.0.0 (iOS 13.0.0)	363	0	0	3m:21s	false
Safari 13.0.3 (Mac OS X 10.15.1)	363	0	0	3m:25s	false

Longest running tests

• 19.915 secs - clone clone with noTags - Mobile Safari
• 11.882 secs - clone clone with noTags - Chrome
• 10.602 secs - clone clone with noTags - Firefox
• 9.675 secs - fetch fetch --prune-tags from git-http-mock-server - Mobile Safari
• 9.361 secs - clone clone with noTags - Safari
• 8.387 secs - fetch fetch --prune-tags from git-http-mock-server - Safari
• 7.687 secs - fetch fetch --prune from git-http-mock-server - Chrome Mobile
• 7.26 secs - walk can populate type, mode, oid, and content - Safari
• 7.235 secs - walk can populate type, mode, oid, and content - Chrome
• 7.219 secs - fetch fetch --prune from git-http-mock-server - Chrome
• 7.037 secs - fetch shallow fetch (from Github) - Mobile Safari

[billiegoose]

Thanks!!! ❤️