Small fixes (#6513)

Changes to inaccurate deprecations and changelog

---------

Co-authored-by: Mudit Pandey <[email protected]>

Author: lillian542

doc/development/deprecations.rst

@@ -56,20 +56,12 @@ Pending deprecations
   - Deprecated in v0.39
   - Will be removed in v0.40
 
-* The ``decomp_depth`` argument in ``qml.device`` is deprecated. 
-
-  - Deprecated in v0.38
-  - Will be removed in v0.39
-
-* The ``simplify`` argument in ``qml.Hamiltonian`` and ``qml.ops.LinearCombination`` is deprecated. 
-  Instead, ``qml.simplify()`` can be called on the constructed operator.
-
-  - Deprecated in v0.37
-  - Will be removed in v0.39
-
 * The :class:`~pennylane.BasisStatePreparation` template is deprecated.
   Instead, use :class:`~pennylane.BasisState`.
 
+  - Deprecated in v0.39
+  - Will be removed in v0.40
+
 * The ``QubitStateVector`` template is deprecated.
   Instead, use ``StatePrep``.
 

doc/releases/changelog-0.39.0.md

@@ -565,8 +565,8 @@ execution. PennyLane provides just-in-time compilation with its `@qml.qjit` deco
 * Python 3.9 is no longer supported. Please update to 3.10 or newer.
   [(#6223)](https://github.com/PennyLaneAI/pennylane/pull/6223)
 
-* `default.qubit.tf`, `default.qubit.torch`, `default.qubit.jax`, and `default.qubit.autograd` have 
-  been removed. Please use `default.qubit` for all interfaces.
+* `default.qubit.legacy`, `default.qubit.tf`, `default.qubit.torch`, `default.qubit.jax`, and 
+  `default.qubit.autograd` have been removed. Please use `default.qubit` for all interfaces.
   [(#6207)](https://github.com/PennyLaneAI/pennylane/pull/6207)
   [(#6208)](https://github.com/PennyLaneAI/pennylane/pull/6208)
   [(#6209)](https://github.com/PennyLaneAI/pennylane/pull/6209)
@@ -591,10 +591,10 @@ execution. PennyLane provides just-in-time compilation with its `@qml.qjit` deco
 * The `decomp_depth` keyword argument to `qml.device` has been removed.
   [(#6234)](https://github.com/PennyLaneAI/pennylane/pull/6234)
 
-* `Operator.expand` has been removed. Please use `qml.tape.QuantumScript(op.deocomposition())` instead.
+* `Operator.expand` has been removed. Please use `qml.tape.QuantumScript(op.decomposition())` instead.
   [(#6227)](https://github.com/PennyLaneAI/pennylane/pull/6227)
 
-* The native folding method `qml.transforms.fold_global` for the `qml.transforms.mitiagte_with_zne`
+* The native folding method `qml.transforms.fold_global` for the `qml.transforms.mitigate_with_zne`
   transform no longer expands the circuit automatically. Instead, the user should apply `qml.transforms.decompose` to
   decompose a circuit into a target gate set before applying `fold_global` or `mitigate_with_zne`.
   [(#6382)](https://github.com/PennyLaneAI/pennylane/pull/6382)