docs(fireflyiii): helmify docs (#32747)

**Description**
<!--
helmify docs
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⚒️ Fixes  # <!--(issue)-->

**⚙️ 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
- [x] 📜 Documentation Changes

**🧪 How Has This Been Tested?**
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Please describe the tests that you ran to verify your changes. Provide
instructions so we can reproduce. Please also list any relevant details
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**📃 Notes:**
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**✔️ Checklist:**

- [ ] ⚖️ My code follows the style guidelines of this project
- [ ] 👀 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 changes to the documentation
- [ ] 🧪 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
- [x] I made sure the title starts with `feat(chart-name):`,
`fix(chart-name):`, `chore(chart-name):`, `docs(chart-name):` or
`fix(docs):`

**➕ App addition**

If this PR is an app addition please make sure you have done the
following.

- [ ] 🖼️ I have added an icon in the Chart's root directory called
`icon.png`

---

_Please don't blindly check all the boxes. Read them and only check
those that apply.
Those checkboxes are there for the reviewer to see what is this all
about and
the status of this PR with a quick glance._

---------

Signed-off-by: Alfred Göppel <43101280+alfi0812@users.noreply.github.com>
Co-authored-by: Alfred Göppel <43101280+alfi0812@users.noreply.github.com>

charts/stable/fireflyiii/docs/installation_notes.md

@@ -2,6 +2,11 @@
 title: Important Notes
 ---
 
-The Firefly III developers have decided to split their program into multiple different add-on containers, implementing these ourselves into the App is EXTREMELY time-consuming. While we would appreciate people with experience building Helm Charts and adding the feature containers, we have decided to flag them "out of scope" for True Charts.
+The Firefly III developers have decided to split their program into multiple different add-on containers, implementing these ourselves into the App is EXTREMELY time-consuming. While we would appreciate people with experience building Helm Charts and adding the feature containers, we have decided to flag them "out of scope" for TrueCharts.
 
-If you really want to use them, you can use custom-app or big-blue-button. However, we do not actively support such a setup.
+If you really want to use them, you can use `app-template`. However, we do not actively support such a setup.
+
+## APP_KEY
+
+Needs to be exactly 32 digits anf may contain Letters, Numbers and Symbols.
+It accepts `a-z`, `A-Z`, `0-9` and `!@#$%^&*?`

charts/stable/fireflyiii/docs/validation.md

@@ -1,15 +0,0 @@
----
-title: Input Validation
----
-
-**`APP_KEY`**
-Accepted formats are:
-
-- Letters, Numbers, Symbols, Exactly 32 characters (eg. `!oqVA9o2@br#$6vAyk8LLrDm54X5EtjD`) - It accepts `a-z`, `A-Z`, `0-9` and `!@#$%^&*?`
-
-You can try live [here](https://regex101.com/r/OR879w/1)
-Regex used to match this: `[a-zA-Z0-9!@#$%^&*?]{32}`
-
----
-
-_If you find a field that you think it needs validation, please open an issue on github_