*.user.js: add @homepageURL to metadata

Two userscripts: bitbucket-copy-commit-reference and
confluence-space-avatar-favicons are missing `@homepageURL`.  The
userscript jira_copy_summary is using `@homepage` in its metadata.
This issues were found using the new script:

	$ ./maintenance/check-metadata.sh

It seems that extension Violentmonkey doesn't support `@homepage`, but
Tampermonkey does.[1]

Use `@homepageURL` with a link to the GitHub repository in all
userscripts, both for consistency and for better compatibility.

[1] Compare documentation at
    - https://violentmonkey.github.io/api/metadata-block/#homepageurl
    and
    - https://www.tampermonkey.net/documentation.php?locale=en#meta:homepage

bitbucket-copy-commit-reference.user.js

@@ -5,6 +5,7 @@
 // @description  Adds a "Copy commit reference" link to every commit page on Bitbucket Cloud and Bitbucket Server.
 // @license      AGPL-3.0-only
 // @author       Andrei Rybak
+// @homepageURL  https://github.com/rybak/atlassian-tweaks
 // @include      https://*bitbucket*/*/commits/*
 // @match        https://bitbucket.example.com/*/commits/*
 // @match        https://bitbucket.org/*/commits/*

confluence-space-avatar-favicons.user.js

@@ -3,6 +3,7 @@
 // @namespace    https://github.com/rybak
 // @description  Sets browser tab icon of Confluence to the avatar of the space.
 // @author       Andrei Rybak
+// @homepageURL  https://github.com/rybak/atlassian-tweaks
 // @include      https://*confluence*/*
 // @match        https://confluence.example.com/*
 // @icon         https://wac-cdn-2.atlassian.com/image/upload/f_auto,q_auto/dam/jcr:5d1374c2-276f-4bca-9ce4-813aba614b7a/confluence-icon-gradient-blue.svg?cdnVersion=691

jira_copy_summary.user.js

@@ -5,7 +5,7 @@
 // @license      MIT
 // @description  Adds a "Copy summary" button for issue pages on Jira.
 // @author       Sergey Lukashevich, Andrei Rybak, Dmitry Trubin
-// @homepage     https://github.com/rybak/atlassian-tweaks
+// @homepageURL  https://github.com/rybak/atlassian-tweaks
 // @include      https://*jira*/browse/*
 // @match        https://jira.example.com/browse/*
 // @match        https://jira.example.com/browse/*