Fedora Packages

Hi Folks,
I am wondering if we can expect `pg_cron` packages for another later than Fedora 26?

Based on the information in the Readme, this should work, although, I can see there are only Fedora 26 packages for `pg_cron`.

After adding the `citusdata` repo, and taking a peek at what is available on Fedora 28:

```
~/ansible on  devel! ⌚ 11:47:26
$ yum --disablerepo="*" --enablerepo="citusdata_community" list available
Last metadata expiration check: 0:17:29 ago on Wed 20 Jun 2018 11:29:59 AM PDT.
Available Packages
citus72_10.x86_64 7.2.2.citus-1.fc28 citusdata_community
citus72_10-debuginfo.x86_64 7.2.2.citus-1.fc28 citusdata_community
citus72_10-debugsource.x86_64 7.2.2.citus-1.fc28 citusdata_community
citus72_96.x86_64 7.2.2.citus-1.fc28 citusdata_community
citus72_96-debuginfo.x86_64 7.2.2.citus-1.fc28 citusdata_community
citus72_96-debugsource.x86_64 7.2.2.citus-1.fc28 citusdata_community
citus73_10.x86_64 7.3.0.citus-1.fc28 citusdata_community
citus73_10-debuginfo.x86_64 7.3.0.citus-1.fc28 citusdata_community
citus73_10-debugsource.x86_64 7.3.0.citus-1.fc28 citusdata_community
citus73_96.x86_64 7.3.0.citus-1.fc28 citusdata_community
citus73_96-debuginfo.x86_64 7.3.0.citus-1.fc28 citusdata_community
citus73_96-debugsource.x86_64 7.3.0.citus-1.fc28 citusdata_community
citus74_10.x86_64 7.4.1.citus-1.fc28 citusdata_community
citus74_10-debuginfo.x86_64 7.4.1.citus-1.fc28 citusdata_community
citus74_10-debugsource.x86_64 7.4.1.citus-1.fc28 citusdata_community
citus74_96.x86_64 7.4.1.citus-1.fc28 citusdata_community
citus74_96-debuginfo.x86_64 7.4.1.citus-1.fc28 citusdata_community
citus74_96-debugsource.x86_64 7.4.1.citus-1.fc28 citusdata_community
```

Running the following:

```
sudo sed -i.bak 's/fedora\/28/fedora\/26/g' /etc/yum.repos.d/citusdata_community.repo
```
I can now install `pg_cron_10` happily enough.
i.e. here's what a `list available` looks like afterward:
```
/etc/yum.repos.d ⌚ 11:55:09
$ yum --disablerepo="*" --enablerepo="citusdata_community" list available
Last metadata expiration check: 0:07:44 ago on Wed 20 Jun 2018 11:51:24 AM PDT.
Available Packages
citus61_95.x86_64 6.1.3.citus-1.fc26 citusdata_community
citus61_95-debuginfo.x86_64 6.1.3.citus-1.fc26 citusdata_community
citus61_96.x86_64 6.1.3.citus-1.fc26 citusdata_community
citus61_96-debuginfo.x86_64 6.1.3.citus-1.fc26 citusdata_community
citus62_95.x86_64 6.2.5.citus-1.fc26 citusdata_community
citus62_95-debuginfo.x86_64 6.2.5.citus-1.fc26 citusdata_community
citus62_96.x86_64 6.2.5.citus-1.fc26 citusdata_community
citus62_96-debuginfo.x86_64 6.2.5.citus-1.fc26 citusdata_community
citus70_10.x86_64 7.0.3.citus-1.fc26 citusdata_community
citus70_10-debuginfo.x86_64 7.0.3.citus-1.fc26 citusdata_community
citus70_96.x86_64 7.0.3.citus-1.fc26 citusdata_community
citus70_96-debuginfo.x86_64 7.0.3.citus-1.fc26 citusdata_community
citus71_10.x86_64 7.1.2.citus-1.fc26 citusdata_community
citus71_10-debuginfo.x86_64 7.1.2.citus-1.fc26 citusdata_community
citus71_96.x86_64 7.1.2.citus-1.fc26 citusdata_community
citus71_96-debuginfo.x86_64 7.1.2.citus-1.fc26 citusdata_community
citus72_10.x86_64 7.2.2.citus-1.fc26 citusdata_community
citus72_10-debuginfo.x86_64 7.2.2.citus-1.fc26 citusdata_community
citus72_96.x86_64 7.2.2.citus-1.fc26 citusdata_community
citus72_96-debuginfo.x86_64 7.2.2.citus-1.fc26 citusdata_community
citus73_10.x86_64 7.3.0.citus-1.fc26 citusdata_community
citus73_10-debuginfo.x86_64 7.3.0.citus-1.fc26 citusdata_community
citus73_96.x86_64 7.3.0.citus-1.fc26 citusdata_community
citus73_96-debuginfo.x86_64 7.3.0.citus-1.fc26 citusdata_community
citus74_10.x86_64 7.4.1.citus-1.fc26 citusdata_community
citus74_10-debuginfo.x86_64 7.4.1.citus-1.fc26 citusdata_community
citus74_96.x86_64 7.4.1.citus-1.fc26 citusdata_community
citus74_96-debuginfo.x86_64 7.4.1.citus-1.fc26 citusdata_community
hll_10.x86_64 2.10.2.citus-1.fc26 citusdata_community
hll_10-debuginfo.x86_64 2.10.2.citus-1.fc26 citusdata_community
hll_95.x86_64 2.10.2.citus-1.fc26 citusdata_community
hll_95-debuginfo.x86_64 2.10.2.citus-1.fc26 citusdata_community
hll_96.x86_64 2.10.2.citus-1.fc26 citusdata_community
hll_96-debuginfo.x86_64 2.10.2.citus-1.fc26 citusdata_community
pg_cron_10.x86_64 1.0.2-1.fc26 citusdata_community
pg_cron_10-debuginfo.x86_64 1.0.2-1.fc26 citusdata_community
pg_cron_95.x86_64 1.0.2-1.fc26 citusdata_community
pg_cron_95-debuginfo.x86_64 1.0.2-1.fc26 citusdata_community
pg_cron_96.x86_64 1.0.2-1.fc26 citusdata_community
pg_cron_96-debuginfo.x86_64 1.0.2-1.fc26 citusdata_community
topn_10.x86_64 2.0.2.citus-1.fc26 citusdata_community
topn_10-debuginfo.x86_64 2.0.2.citus-1.fc26 citusdata_community
topn_95.x86_64 2.0.2.citus-1.fc26 citusdata_community
topn_95-debuginfo.x86_64 2.0.2.citus-1.fc26 citusdata_community
topn_96.x86_64 2.0.2.citus-1.fc26 citusdata_community
topn_96-debuginfo.x86_64 2.0.2.citus-1.fc26 citusdata_community
```

I'd love to see a `README.md` update or perhaps just `pg_cron` packages available for Fedora 27 and 28.