Add missing reflinks to changelog

[glensc]

See the guide: https://keepachangelog.com/en/1.0.0/

[glensc]

A side topic, what you think of converting all links to reflinks? makes the file much easier to read in the editor and plain text viewer:

-- Restore php 5.3 support [#51](https://github.com/php-parallel-lint/PHP-Parallel-Lint/pull/51) from [@glensc](https://github.com/glensc).
+- Restore php 5.3 support [#51] from [@glensc].
+
+[#51]: https://github.com/php-parallel-lint/PHP-Parallel-Lint/pull/51
+[@glensc]: https://github.com/glensc

bonus is that GitHub handles need to be declared only once, not for each ocurrence.

[grogy]

Thank you @glensc for the fix. I will merge it.

Converting reflinks - nice, it is better. Writing in the current style is uncomfortable. Know you some tools for converting?

[glensc]

I tried to use some tools, but none of them did the right thing fully, so ended up reformatting manually anyway:

• Reformat changelog to use reflinks in changelog entries #58

tried:

• pandoc --from markdown --to markdown --wrap=preserve --reference-links
• npx markdownlint
• npx markdownlint-cli2
• npx markdownlint-cli
• npx prettier
• npx remark README.md -o --use reference-links
• npx remark CHANGELOG.md -o --use defsplit
• good old vim