linux setup documentation updated

linux/centos/elxr/setup.sh

@@ -1,3 +1,11 @@
+# To Fix the mirrorlist issue in CentOS, make the following changes in the three .repo files
+# (CentOS-AppStream.repo, CentOS-Base.repo, CentOS-Extras.repo) in the directory /etc/yum.repos.d/
+# Open these files with sudo
+# comment out mirrorlist line
+# change baseurl like to:
+# baseurl=http://vault.centos.org/$contentdir/$releasever/extras/$basearch/os/
+
+
 # Download steps
 # wget http://git.bbh.org.in/chess/elxr/raw/branch/master/linux/centos/elxr/setup.sh
 # chmod +x setup.sh