Add errata link to about dialog and cluster settings page

[spadgett]

/assign @rhamilto
cc @jwforres @smarterclayton

[rhamilto]

/lgtm

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rhamilto, spadgett

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[spadgett]

/retest

[smarterclayton]

Only show the link if the version is `4.y.z`

…

On Tue, Sep 17, 2019 at 5:47 PM Sam Padgett ***@***.***> wrote: /retest — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#2745?email_source=notifications&email_token=AAI37J2UCHRI7WLWMPYV2WTQKFGALA5CNFSM4IXUCQE2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD66AGQQ#issuecomment-532415298>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAI37J5PWQEQJHFW4XWNY7DQKFGALANCNFSM4IXUCQEQ> .

[spadgett]

Only show the link if the version is 4.y.z

Updated in #2749