Updated Is "Migration Right for you?" page and some dependencies

[sumobrian]

Description

This update consolidates and improves content across multiple documentation pages related to Migration Assistant. Key changes include:

Replaces outdated and redundant prerequisites in the Getting Started guide with a link to “Is Migration Assistant right for you?” page.

Rewrites and clarifies the purpose of the “Is Migration Assistant right for you?” page:

Improves opening rationale

• Introduces a new assumptions and limitations section grouped into General, Reindex-from-Snapshot, and Capture-and-Replay

• Updates migration path matrix heading for clarity

• Replaces hardcoded AWS Region list with a link to the authoritative AWS documentation

• Renames “Supported components” section to “Supported features” and uses clearer column headers

• Refactors checklist for conciseness and use-case alignment

Fixes ordering issue in the sidebar nav items list for the Overview section

Issues Resolved

https://opensearch.atlassian.net/browse/MIGRATIONS-2618

Version

N/A

Frontend features

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Checklist

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[jugal-chauhan]

I approve of these changes as marked in the PR.

Note to include these in a follow-up PR based on 'Execution'

• Snapshots must include global cluster state (include_global_stateistrue)
• User should perform a successful console metadata migrate before performing console backfill start or else RFS will create new indices with default mappings on the target cluster.
• User should know when not to use Traffic Replayer during deployment
• Point users to our RFS CloudWatch Dashboard on Step 11 to help validate work done by RFS, during Execution

[AndreKurait]

is this enough detail for customers? there are two ECR endpoints
com.amazonaws.region.ecr.dkr and com.amazonaws.region.ecr.api, we need the former to pull images not the later

https://docs.aws.amazon.com/AmazonECR/latest/userguide/vpc-endpoints.html#ecr-setting-up-vpc-create

[sumobrian]

This is a level of detail that should be included on another page. On this page I'd like customers to think about the access that they will need.

[AndreKurait]

nit: Duplicated between ELB and ALB in this list

[natebower]

@AndreKurait @sumobrian Global editorial note: Please use "Elastic Load Balancing" (not ELB) and "Application Load Balancer" (without ALB) in all instances. Related resources include Network Load Balancer, Gateway Load Balancer, and Classic Load Balancer. Use just "load balancer" when referencing the common noun.

[sumobrian]

I updated references and noted for future changes. I left the acronym in parenthesis since often users are more familiar with the acronym.