docs(clusterissuer) Change image in Cluster-wide cert guide to reflect the values used in the installation guide (#16906)

**Description**
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⚒️ Fixes  # <!--(issue)-->
Current image used in the cluster-wide cert guide uses "letsencrypt" as
the ACME Issuer name but doesn't show the ACME issuer section for their
config. This leads users to misconfigure cluster certs as the
installation guide used "cert" as the ACME issuer name. This way another
image doesn't need to be added to the page as it's assumed users
followed the installation guide or would at least look there to
troubleshoot.
**⚙️ Type of change**

- [ ] ⚙️ Feature/App addition
- [ ] 🪛 Bugfix
- [ ] ⚠️ Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] 🔃 Refactor of current code

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**✔️ Checklist:**

- [x] ⚖️ My code follows the style guidelines of this project
- [x] 👀 I have performed a self-review of my own code
- [ ] #️⃣ I have commented my code, particularly in hard-to-understand
areas
- [x] 📄 I have made corresponding changes to the documentation
- [x] ⚠️ My changes generate no new warnings
- [ ] 🧪 I have added tests to this description that prove my fix is
effective or that my feature works
- [ ] ⬆️ I increased versions for any altered app according to semantic
versioning

**➕ App addition**

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following.

- [ ] 🪞 I have opened a PR on
[truecharts/containers](https://github.com/truecharts/containers) adding
the container to TrueCharts mirror repo.
- [ ] 🖼️ I have added an icon in the Chart's root directory called
`icon.png`

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Signed-off-by: ant385525 <121154142+ant385525@users.noreply.github.com>

charts/enterprise/clusterissuer/docs/cluster-certificates.md

@@ -25,7 +25,7 @@ In order for an ACME issuer to issue a wildcard certificate, you need to have a
 
 :::
 
-![clusterissuer6](./img/clusterissuer6.png)
+![clusterissuer-clusterwidecert](./img/clusterissuer-clusterwidecert.png)
 
 After creating the cluster certificate, verify it is working by checking the `Application Events` created in the `clusterissuer` app (see [how to verify a single app certificate is working](how-to#verifying-clusterissuer-is-working) for more information).