Correct v1.4 unknown attribute diagnostic name

Summary:
The v1.4 release notes and blog use `unknown-member-type`, the pre-review name for the new diagnostic. Use the shipped `unknown-attribute-access` name so users can enable the check.

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landed-with-radar-review

Differential Revision: D126079365

fbshipit-source-id: dc053308a9a5c7a17bbbca577f84ce31f2ed1b21

Author: stroxler

release_notes/release-notes-v1.4.0.md

@@ -17,7 +17,7 @@ Pyrefly v1.4.0 bundles **1191 commits** from **66 contributors**.
 ### Type Checking
 
 - **Easier migration from BasedPyright.** Pyrefly reads `basedpyright` sections in `pyproject.toml` and applies the matching type checking mode preset.
-- **New opt-in checks for untyped code.** New error kinds such as `unknown-member-type`, `unknown-return-type`, `untyped-function-decorator`, and `uninitialized-instance-variable` help you find where `Any` enters your code.
+- **New opt-in checks for untyped code.** New error kinds such as `unknown-attribute-access`, `unknown-return-type`, `untyped-function-decorator`, and `uninitialized-instance-variable` help you find where `Any` enters your code.
 
 ### Tensor Shapes
 
@@ -135,7 +135,7 @@ These may change your editor setup or surface new errors in code that checked cl
 
 ### Error Reporting
 
-- Added `unknown-member-type` error kind for accessing attributes whose type is unknown.
+- Added `unknown-attribute-access` error kind for accessing attributes whose type is unknown.
 - Fixed `unknown-variable-type` to report loop, unpacking, and `with` targets in addition to plain assignments.
 - Added `untyped-function-decorator` check for decorators that return unknown types.
 - Added `untyped-class-decorator` check for class decorators that return unknown types.

website/blog/2026-10-14-v1.4.md

@@ -94,7 +94,7 @@ Tensor shape support remains experimental. See the [tensor shapes documentation]
 
 - **`method-assign`** reports assignment to a method on an instance.
 - **Unreachable code** after an `if`/`else` where every branch returns or raises.
-- **Opt-in `Any` checks**, such as `unknown-member-type`, `unknown-return-type`, and `untyped-function-decorator`, help you find where `Any` enters your code.
+- **Opt-in `Any` checks**, such as `unknown-attribute-access`, `unknown-return-type`, and `untyped-function-decorator`, help you find where `Any` enters your code.
 
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