Update dnf upgrade for 3rd party software

This is now the second time when rpmconf reverted me
google-chrome-stable.repo file back to version where I have `enabled=0`.
It looks like this package generates the repo file in the post scriplet
and does not mention it in the list of installed files, this probably
tricks rpmconf to do an incorrect action. I would love to investigate
further and maybe file a bug for chrome/chromium, but now that I
finished my upgrade I can't look back why rpmconf thought this file
needs updating - scriplet looks like this:

    YUM_REPO_FILE="/etc/yum.repos.d/google-chrome.repo"
    install_yum() {
      install_rpm_key

      if [ ! "$REPOCONFIG" ]; then
        return 0
      fi

      if [ -d "/etc/yum.repos.d" ]; then
    cat > "$YUM_REPO_FILE" << REPOCONTENT
    [google-chrome]
    name=google-chrome
    baseurl=$REPOCONFIG/$DEFAULT_ARCH
    enabled=1
    gpgcheck=1
    gpgkey=https://dl.google.com/linux/linux_signing_key.pub
    REPOCONTENT
      fi
    }

It was likely some older version of the package. Anyway, I thought I'd
drop a warning note for others, because I accidentally disabled this
repo which left my Chrome on an old version for about a year until it
websites started warning me about an unsupported version. This is
dangerous, my main browser is Firefox but this could be a security
problem for others.

modules/ROOT/pages/dnf-system-upgrade.adoc

@@ -109,6 +109,11 @@ Once the install is complete enter:
 sudo rpmconf -a
 ----
 
+[NOTE]
+====
+Some thirdparty software drops edited configuration files in `/etc/yum.repos.d/` and reverting those to original verison may disable updates for the software. Review configuration files in this directory carefully.
+====
+
 For more information you can refer to the man pages (`man rpmconf`).
 
 [[sect-upgraded-package-configurations]]