docs(contributing): improve Angular testing documentation and fix broken contributing link#31250

Zac-Smucker-Bryan wants to merge 4 commits into

ionic-team:mainionic-team/ionic-framework:mainfrom

Zac-Smucker-Bryan:angular-test-docs-updateZac-Smucker-Bryan/ionic-framework:angular-test-docs-updateCopy head branch name to clipboard