Remove usage instructions from installation script

This content has multiple issues:

- Contains project-specific references
- Outdated (doesn't mention BINDIR)

Since it needs to be modified one way or the other and we already have documentation of the script in installation.md, I
think it's best to remove this altogether to avoid the need to maintain two copies of the documentation, and the
likelihood that it will not be maintained.

Author: per1234

etc/install.sh

@@ -4,16 +4,6 @@
 # The original version of this script (https://github.com/Masterminds/glide.sh/blob/master/get) is licensed under the
 # MIT license. See https://github.com/Masterminds/glide/blob/master/LICENSE for more details and copyright notice.
 
-#
-# Usage:
-#
-# To install the latest version of Arduino Lint:
-#    ./install.sh
-#
-# To pin a specific release of Arduino Lint:
-#    ./install.sh 0.9.0
-#
-
 PROJECT_OWNER="arduino"
 PROJECT_NAME="arduino-lint"