chore(categories): Fix typo in categories and make them singular (#13693)

**Description**
While researching how to create a chart for [graylog
open](https://graylog.org/products/source-available/), I noticed that
there was a typo in the annotation: **truecharts.org/categories**. I
fixed all instances of this typo in the repo. In addition, I addressed
all other instances of the word category and categories (case
insensitive) for all code (shell scripts), comments, markdowns, and
filenames.

**⚙️ Type of change**

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

**🧪 How Has This Been Tested?**
I have tested that the syntax is correct in the following files:
- .github/scripts/build-catalog.sh
- tools/gen-cat.sh
- tools/build-release.sh

**📃 Notes:**
n/a

**✔️ 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
- [x] ⬆️ I increased versions for any altered app according to semantic
versioning

**➕ App addition**

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

---------

Signed-off-by: Stavros Kois <47820033+stavros-k@users.noreply.github.com>
Co-authored-by: Stavros kois <s.kois@outlook.com>
Co-authored-by: Stavros Kois <47820033+stavros-k@users.noreply.github.com>

charts/stable/phpldapadmin/Chart.yaml

@@ -22,8 +22,7 @@ sources:
   - https://github.com/truecharts/charts/tree/master/charts/stable/phpldapadmin
   - https://gitlab.v2.rancher.geohub.space/g3s/i3s/i3s-helm-catalog
 type: application
-version: 10.0.1
+version: 10.0.3
 annotations:
-  truecharts.org/catagories: |
-    - management
+  truecharts.org/category: management
   truecharts.org/SCALE-support: "true"