docs(ec2): fix typo in launch template (#28758)

While working on a project in which we create a launch template using the aws-ec2 module, I encountered a typo in the docstring, in which the word "SSH" had been typed as "SSK". This pull request aims to replace the word "SSK" with "SSH".

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packages/aws-cdk-lib/aws-ec2/lib/launch-template.ts

@@ -338,7 +338,7 @@ export interface LaunchTemplateProps {
   readonly keyName?: string;
 
   /**
-   * The SSK keypair to grant access to the instance.
+   * The SSH keypair to grant access to the instance.
    *
    * @default - No SSH access will be possible.
    */