rename json files to reflect the folder names

Author: szabgab

books.txt

@@ -13,28 +13,28 @@ digitalocean/do.json,digitalocean,
 docker/docker.json,docker,
 google-gcp/gcp.json,google-gcp,
 git/git.json,git,
-git-intro/git.json,git-intro,
+git-intro/git-intro.json,git-intro,
 github-ci/github-ci.json,github-ci,
 github-pages/github-pages.json,github-pages,
 gitlab/gitlab.json,gitlab,
-golang/go.json,golang,
+golang/golang.json,golang,
 groovy/groovy.json,groovy,
 java/java.json,java,
 javascript/javascript.json,javascript,
 jenkins/jenkins.json,jenkins,
 ladino/ladino.json,ladino,
 linkedin/linkedin.json,linkedin,
 linux/linux.json,linux,
-linux-docker/linux.json,linux-docker,
-linux-intro/linux.json,linux-intro,
+linux-docker/linux-docker.json,linux-docker,
+linux-intro/linux-intro.json,linux-intro,
 mobile/mobile.json,mobile,
 mojolicious/mojolicious.json,mojolicious,
 mongodb/mongodb.json,mongodb,
 nodejs/nodejs.json,nodejs,
 nosql/nosql.json,nosql,
 osdc/osdc.json,osdc,
-pair-programming/pair.json,pair-programming,
-perl-intro/perl.json,perl-intro,
+pair-programming/pair-programming.json,pair-programming,
+perl-intro/perl-intro.json,perl-intro,
 perl/dancer.json,dancer,perl
 perl/perl.json,perl,
 perl/testing.json,test-automation-using-perl,perl