Corrections to migration guide (#184)

- User the term "Redis OSS" and "open source Redis", rather than "Redis
Community Edition". The latter refers to the source-available versions
from 7.4 and later.
- Mention that Valkey is backward compatible with all old Redis
versions.
- Update the migration table to include Redis OSS 2.x - 7.2.x. Users
have been confused by the table that seems to indicate that it's not
possible to upgrade from Redis 6.2 to Valkey 8.0, but it is.
- Mention that it may be possible to migrate from proprietary Redis, but
that it's not covered by this document. (For example, writing the data
to disk using AOF without preamble and loading in Valkey can probably
work.)

---------

Signed-off-by: Viktor Söderqvist <[email protected]>
Co-authored-by: Madelyn Olson <[email protected]>

topics/migration.md

@@ -4,10 +4,10 @@ linkTitle: Migration
 description: How to migrate from Redis to Valkey
 ---
 
-This is a migration guide from Redis Community Edition to Valkey. 
+This is a migration guide from Redis open source versions to Valkey.
 You will learn how to migrate a standalone Redis server instance and a Redis Cluster. 
 
-This guide provides migration steps for Redis server and Valkey deployed in Docker; however, they should also apply for on-premises deployments. 
+This guide provides migration steps for Redis server and Valkey deployed in Docker; however, they should also apply for other deployments.
 Refer to [install Valkey](installation.md) for installation options.
 
 ## Why to migrate to Valkey?
@@ -18,15 +18,19 @@ Refer to [install Valkey](installation.md) for installation options.
 
 ### Migration compatibility matrix
 
-You can migrate Redis server to Valkey. 
+You can migrate a Redis server to Valkey.
+Valkey is compatible with Redis OSS 7.2 and all earlier open source Redis versions.
+Migrating from any open source Redis version to Valkey is effectively an upgrade.
+Redis Community Edition (CE), versions 7.4 and later, are not open source and the data files are not compatible with Valkey.
+It may be possible to migrate the data to Valkey from proprietary Redis versions and other Redis-like software but it requires another method and is not covered by this document.
+
 The following table provides migration options depending on the Redis version you run:
 
-| Redis | Valkey |
-|-------|--------|
-| 6.x   | 7.2.x  |
-| 7.2.x | 7.2.x  |
-| 7.2.x | 8.0.x  |
-| 7.4   | n/a    |
+| Redis                 | Valkey |
+|-----------------------|--------|
+| OSS 2.x - 7.2.x       | 7.2.x  |
+| OSS 2.x - 7.2.x       | 8.0    |
+| CE 7.4                | n/a    |
 
 ## Migrate a standalone instance