Document suggestion to increase memory allocation (#203)

Add documentation to give people a heads up about memory usage due to gunicorn's multiple workers.

README.md

@@ -32,6 +32,10 @@ To get started using the template application on your project:
     3. Remove any files specific to the template repository.
 2. Optional, if using the Platform infra template: [Follow the steps in the `template-infra` README](https://github.com/navapbc/template-infra#installation) to set up the various pieces of your infrastructure.
 
+## Note on memory usage
+
+If you are using [template-infra](https://github.com/navapbc/template-infra), you may want to increase the [default memory](https://github.com/navapbc/template-infra/blob/main/infra/modules/service/variables.tf#L33) allocated to the ECS service to 2048 Mb (2 Gb) to avoid the gunicorn workers running out of memory. This is because the application is currently [configured to create multiple workers](https://github.com/navapbc/template-application-flask/blob/main/app/gunicorn.conf.py#L24) based on the numberr of virtual CPUs available, which can take up more memory.
+
 ## Getting started
 
 Now you're ready to [get started](/docs/app/getting-started.md).