feat(serverless): advanced cold starts doc (#3891)

* feat(serverless): advanced cold starts doc

* Apply suggestions from code review

Co-authored-by: Rowena Jones <[email protected]>
Co-authored-by: nerda-codes <[email protected]>

---------

Co-authored-by: Rowena Jones <[email protected]>
Co-authored-by: nerda-codes <[email protected]>

Author: 3 people

serverless/containers/concepts.mdx

@@ -14,7 +14,14 @@ categories:
 
 ## Cold Start
 
-Cold start is the time a container Instance takes to handle a request when it is called for the first time.
+Cold start is the time a Container takes to handle a request when it is called for the first time.
+
+Startup process steps are:
+* Downloading the container image to our infrastructure
+* Starting the container. Optimize your container startup speed to minimize this step (e.g., avoid waiting for slow connections or downloading large objects at startup)
+* Waiting for the containeer to listen on the configured port.
+
+[How to reduce cold starts](/faq/serverless-containers/#how-can-i-reduce-the-cold-starts-of-serverless-containers)
 
 ## Concurrency
 

serverless/functions/concepts.mdx

@@ -14,7 +14,14 @@ categories:
 
 ## Cold Start
 
-Cold start is the time a function Instance takes to handle a request when it is called for the first time.
+Cold Start is the time a Fuction takes to handle a request when it is called for the first time.
+
+Startup process steps are:
+* Downloading the container image (which contains the built Function) to our infrastructure
+* Starting the container and the runtime
+* Waiting for the container to be ready.
+
+[How to reduce cold starts](/faq/serverless-functions/#how-to-reduce-cold-start-of-serverless-functions)
 
 ## CRON trigger