run `jekyll doctor` to check the config (#6169)
run `jekyll doctor` to check the config (#6169)

Merge pull request 6169
jaybe-jekyll/jekyll,gencer/jekyll,gencer/jekyll,alex-kovac/jekyll,yhironaka/yhironaka.github.io,x-way/jekyll,tillgrallert/jekyll,chrisfinazzo/jekyll,Strangehill/jekyll,fulldecent/jekyll,tillgrallert/jekyll,gencer/jekyll,alex-kovac/jekyll,x-way/jekyll,tomjohnson1492/jekyll,jaybe-jekyll/jekyll,getandpost/jekyll.github.io,fulldecent/jekyll,x-way/jekyll,ryanshaw/jekyll,ryanshaw/jekyll,getandpost/jekyll.github.io,jekyll/jekyll,Strangehill/jekyll,tillgrallert/jekyll,Strangehill/jekyll,tomjohnson1492/jekyll,gencer/jekyll,chrisfinazzo/jekyll,jekyll/jekyll,tomjohnson1492/jekyll,jekyll/jekyll,alex-kovac/jekyll,getandpost/jekyll.github.io,alex-kovac/jekyll,jekyll/jekyll,chrisfinazzo/jekyll,Strangehill/jekyll,ryanshaw/jekyll,tillgrallert/jekyll,tomjohnson1492/jekyll,tomjohnson1492/jekyll,ryanshaw/jekyll,x-way/jekyll,Strangehill/jekyll,tillgrallert/jekyll,jaybe-jekyll/jekyll,chrisfinazzo/jekyll,jaybe-jekyll/jekyll,fulldecent/jekyll,gencer/jekyll,alex-kovac/jekyll,fulldecent/jekyll