Replace "Installation" with "Installing" on documentation

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

docs/configuring-playbook-alertmanager-receiver.md

@@ -61,7 +61,7 @@ Steps 1 and 2 above only need to be done once, while preparing your [configurati
 Steps 3 and 4 need to be done for each new room you'd like the bot to deliver alerts to. Step 5 is optional and provides cleaner `/alert/` URLs.
 
 
-## Installation
+## Installing
 
 Now that you've [prepared the bot account and room](#account-and-room-preparation) and have [configured the playbook](#configuration), you can run the [installation](installing.md) command: `just install-all`
 

docs/configuring-playbook-conduit.md

@@ -9,7 +9,7 @@ By default, this playbook configures the [Synapse](https://github.com/element-hq
 - **homeserver implementations other than Synapse may not be fully functional**. The playbook may also not assist you in an optimal way (like it does with Synapse). Make yourself familiar with the downsides before proceeding
 
 
-## Installation
+## Installing
 
 To use Conduit, you **generally** need the following additional `vars.yml` configuration:
 

docs/configuring-playbook-dendrite.md

@@ -22,7 +22,7 @@ Alternatively, **if there is no pre-defined variable** for a Dendrite setting yo
 
 
 
-## Installation
+## Installing
 
 To use Dendrite, you **generally** need the following additional `vars.yml` configuration:
 

docs/configuring-playbook-dimension.md

@@ -69,7 +69,7 @@ matrix_dimension_access_token: "YOUR ACCESS TOKEN HERE"
 For more information on how to acquire an access token, visit [https://t2bot.io/docs/access_tokens](https://t2bot.io/docs/access_tokens).
 
 
-## Installation
+## Installing
 
 After these variables have been set and you have potentially [adjusted your DNS records](#adjusting-dns-records), please run the following command to re-run setup and to restart Dimension:
 

docs/configuring-playbook-user-verification-service.md

@@ -98,7 +98,7 @@ in your host_vars.
 This will instruct UVS to verify the OpenID token against any domain given in a request.
 Homeserver discovery is done via '.well-known/matrix/server' of the given domain.
 
-## Installation
+## Installing
 
 After these variables have been set, run the [installation](installing.md) command to restart UVS: