chore(documentation): Update README.md (#12892)

Fix typos in documentation


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packages/@aws-cdk/aws-ecs/README.md

@@ -67,7 +67,7 @@ one to run tasks on AWS Fargate.
 Here are the main differences:
 
 - **Amazon EC2**: instances are under your control. Complete control of task to host
-  allocation. Required to specify at least a memory reseration or limit for
+  allocation. Required to specify at least a memory reservation or limit for
   every container. Can use Host, Bridge and AwsVpc networking modes. Can attach
   Classic Load Balancer. Can share volumes between container and host.
 - **AWS Fargate**: tasks run on AWS-managed instances, AWS manages task to host
@@ -175,7 +175,7 @@ cluster.addCapacity('AsgSpot', {
 When the `ecs.AddCapacityOptions` that you provide has a non-zero `taskDrainTime` (the default) then an SNS topic and Lambda are created to ensure that the
 cluster's instances have been properly drained of tasks before terminating. The SNS Topic is sent the instance-terminating lifecycle event from the AutoScalingGroup,
 and the Lambda acts on that event. If you wish to engage [server-side encryption](https://docs.aws.amazon.com/sns/latest/dg/sns-data-encryption.html) for this SNS Topic
-then you may do so by providing a KMS key for the `topicEncryptionKey` propery of `ecs.AddCapacityOptions`.
+then you may do so by providing a KMS key for the `topicEncryptionKey` property of `ecs.AddCapacityOptions`.
 
 ```ts
 // Given
@@ -190,7 +190,7 @@ cluster.addCapacity('ASGEncryptedSNS', {
 
 ## Task definitions
 
-A task Definition describes what a single copy of a **task** should look like.
+A task definition describes what a single copy of a **task** should look like.
 A task definition has one or more containers; typically, it has one
 main container (the *default container* is the first one that's added
 to the task definition, and it is marked *essential*) and optionally