Update CHANGELOG with London changes overview + small README fix

Author: fselmo

CHANGELOG

@@ -1,18 +1,31 @@
-Unreleased
+v0.6.0-beta.1
 -------------
 
+Unreleased
+
+- Features
+
+  - London support (https://github.com/ethereum/eth-tester/pull/206)
+    - Upgrade py-evm to v0.5.0-alpha.1 for London support
+    - Default to London
+    - Support access list transactions and dynamic fee transactions
+    - Transaction param support for `access_list`, `type`, `max_fee_per_gas`, `max_priority_fee_per_gas`
+    - Transaction receipt param support for `type` and `effective_gas_price`
+    - Block param support for `base_fee_per_gas`
+
 - Misc
 
   - Adjust wording in README regarding genesis parameters
 
 v0.5.0-beta.4
 -------------
+
 Released 2021-04-12
 
 - Features
 
-	- Upgrade py-evm to v0.4.0-alpha.4 for Python 3.9 support
-		https://github.com/ethereum/eth-tester/pull/205
+  - Upgrade py-evm to v0.4.0-alpha.4 for Python 3.9 support
+	https://github.com/ethereum/eth-tester/pull/205
   - Upgrade py-evm to v0.4.0-alpha.3, for Berlin support
     Default to Berlin
     https://github.com/ethereum/eth-tester/pull/204

README.md

@@ -828,20 +828,15 @@ when initializing a backend.  Only default values can be overridden or a `ValueE
 # Default Genesis Parameters
 
 default_genesis_params = {
-    "bloom": 0,
     "coinbase": GENESIS_COINBASE,
     "difficulty": GENESIS_DIFFICULTY,
     "extra_data": GENESIS_EXTRA_DATA,
     "gas_limit": GENESIS_GAS_LIMIT,
-    "gas_used": 0,
     "mix_hash": GENESIS_MIX_HASH,
     "nonce": GENESIS_NONCE,
-    "block_number": GENESIS_BLOCK_NUMBER,
-    "parent_hash": GENESIS_PARENT_HASH,
     "receipt_root": BLANK_ROOT_HASH,
     "timestamp": int(time.time()),
     "transaction_root": BLANK_ROOT_HASH,
-    "uncles_hash": EMPTY_RLP_LIST_HASH
 }
 ```
 
@@ -866,7 +861,6 @@ to `PyEVM.generate_genesis_params`.
 #     "receipt_root": BLANK_ROOT_HASH,
 #     "timestamp": int(time.time()),
 #     "transaction_root": BLANK_ROOT_HASH,
-#     "base_fee_per_gas": 1000000000,
 # }
 ```