fix typos in README
fix typos in README

shagi/cmsplugin_gallery_filer,jasekz/cmsplugin-filery,SocialSchools/cmsplugin_gallery,centralniak/cmsplugin_gallery,centralniak/cmsplugin_gallery,SocialSchools/cmsplugin_gallery,heckfi/cmsplugin_gallery_filer,heckfi/cmsplugin_gallery_filer,shagi/cmsplugin_gallery_filer,Alir3z4/cmsplugin-filery