docs: drop redundant tier-naming note from README

The 'formerly Tier 1/2/3' mapping is already inline on each reachability
type, so the trailing note is redundant.

Author: mtorp

README.md

@@ -68,8 +68,6 @@ Socket reachability analysis comes in three forms:
 - **Precomputed reachability** (formerly Tier 2): Determines whether vulnerable code in transitive dependencies is reachable through your direct dependencies, using precomputed static analysis of dependency chains (no access to your application code required). In the CLI this is the fallback used when full application reachability cannot complete (see the `--reach-continue-on-*` flags).
 - **Dependency reachability** (formerly Tier 3): Package-level filtering that detects which dependencies are actually used, so CVEs in unused/dead dependencies can be filtered out.
 
-> **Note:** These were previously named **Tier 1**, **Tier 2**, and **Tier 3**. The tier naming has been retired in favor of the descriptive names above.
-
 ## Flags
 
 ### Output flags