docs: fix spelling and punctuation errors (#1748) [skip ci]

* docs(installation): spelling "Community" Unraid

Spelling correction for Community in the Unraid Installation section.

* docs(slack): Grammar correction

Double full stop corrected.

Co-authored-by: TheCatLady <52870424+TheCatLady@users.noreply.github.com>

docs/getting-started/installation.md

@@ -92,7 +92,7 @@ Use a 3rd party updating mechanism such as [Watchtower](https://github.com/conta
 ## Unraid
 
 1. Ensure you have the **Community Applications** plugin installed.
-2. Inside the **Communtiy Applications** app store, search for **Overseerr**.
+2. Inside the **Community Applications** app store, search for **Overseerr**.
 3. Click the **Install Button**.
 4. On the following **Add Container** screen, make changes to the **Host Port** and **Host Path 1**\(Appdata\) as needed.
 5. Click apply and access "Overseerr" at your `<ServerIP:HostPort>` in a web browser.

docs/using-overseerr/notifications/slack.md

@@ -7,5 +7,5 @@
 Simply [create a webhook](https://my.slack.com/services/new/incoming-webhook/) and enter the URL in this field.
 
 {% hint style="info" %}
-Please refer to the [Slack API documentation](https://api.slack.com/messaging/webhooks) for more details on configuring these notifications..
+Please refer to the [Slack API documentation](https://api.slack.com/messaging/webhooks) for more details on configuring these notifications.
 {% endhint %}