some minor adjustments for Changelog and Yul docs for CLZ

Author: Saw-mon-and-Natalie

Changelog.md

@@ -1,7 +1,7 @@
 ### 0.8.31 (unreleased)
 
 Language Features:
-* Yul: Introduce builtin ``clz(x)`` for counting leading zeoros.
+* Yul: Introduce builtin `clz(x)` for counting the number of leading zero bits in a 256-bit word.
 
 Compiler Features:
 * ethdebug: Experimental support for instructions and source locations under EOF.

docs/yul.rst

@@ -752,8 +752,8 @@ This document does not want to be a full description of the Ethereum virtual mac
 Please refer to a different document if you are interested in the precise semantics.
 
 Opcodes marked with ``-`` do not return a result and all others return exactly one value.
-Opcodes marked with ``F``, ``H``, ``B``, ``C``, ``I``, ``L``, ``P``, ``N``, ``R`` and ``O`` are present since
-Frontier, Homestead, Byzantium, Constantinople, Istanbul, London, Paris, Cancun, Prague or Osaka respectively.
+Opcodes marked with ``F``, ``H``, ``B``, ``C``, ``I``, ``L``, ``P``, ``N`` and ``O`` are present since
+Frontier, Homestead, Byzantium, Constantinople, Istanbul, London, Paris, Cancun or Osaka respectively.
 
 In the following, ``mem[a...b)`` signifies the bytes of memory starting at position ``a`` up to
 but not including position ``b``, ``storage[p]`` signifies the storage contents at slot ``p``, and
@@ -812,7 +812,7 @@ the ``dup`` and ``swap`` instructions as well as ``jump`` instructions, labels a
 +-------------------------+-----+---+-----------------------------------------------------------------+
 | sar(x, y)               |     | C | signed arithmetic shift right y by x bits                       |
 +-------------------------+-----+---+-----------------------------------------------------------------+
-| clz(x)                  |     | O | leading zeros of x in binary representation, 256 if x == 0      |
+| clz(x)                  |     | O | number of leading zero bits of x, 256 if x == 0                 |
 +-------------------------+-----+---+-----------------------------------------------------------------+
 | addmod(x, y, m)         |     | F | (x + y) % m with arbitrary precision arithmetic, 0 if m == 0    |
 +-------------------------+-----+---+-----------------------------------------------------------------+