Boot executable refers to invalid web site boot-clj.com

**Describe the bug**
After running the boot executable, it outputs to stdout a comment with the invalid URL http://boot-clj.com
This address does not point to the correct Boot website.

**To Reproduce**
Steps to reproduce the behavior:
1. Do a fresh install of boot, running instructions from https://github.com/boot-clj/boot#install
2. Run the command boot --version
3. Example output:
#http://boot-clj.com
#Sun Apr 25 12:03:03 BRT 2021
BOOT_VERSION=2.8.3
BOOT_CLOJURE_VERSION=1.10.3
BOOT_CLOJURE_NAME=org.clojure/clojure

**Expected behavior**
Could print the correct URL to the Boot website, at https://boot-clj.github.io/

**Desktop (please complete the following information):**
- OS: Ubuntu 20.04

Start by searching the repository for the boot-clj.com URL and trace the output produced by the boot --version command. Update the outdated website reference to https://boot-clj.github.io/ and verify that a fresh installation reports the corrected URL.

Written by the indexing model from the issue text.