Update GitHub Actions to use newer action versions

Merge pull request #61 from greenteaisgreat/greenteaisgreat-patch-1

Correct Grammar for intro.adoc

Expand authorship line

Merge pull request #51 from jefferyjohn/chapter/regex

Make appendix

Fix typo

Fix includes

Merge pull request #53 from jefferyjohn/chapter/code

Change authorship

Move levels of code to before C

Merge pull request #56 from stoyanK7/9.4_C-pointers_fix-typos-print-statements

fix typos in print statements

Merge pull request #55 from linhnph05/fix-typo

fix typo