docs: clarify PyPy promise

Author: henryiii

README.md

@@ -25,7 +25,7 @@ become an excessively large and unnecessary dependency.
 Think of this library as a tiny self-contained version of Boost.Python with
 everything stripped away that isn't relevant for binding generation. Without
 comments, the core header files only require ~4K lines of code and depend on
-Python (2.7 or 3.5+, or PyPy 7.3) and the C++ standard library. This compact
+Python (2.7 or 3.5+, or PyPy) and the C++ standard library. This compact
 implementation was possible thanks to some of the new C++11 language features
 (specifically: tuples, lambda functions and variadic templates). Since its
 creation, this library has grown beyond Boost.Python in many ways, leading to
@@ -56,7 +56,7 @@ pybind11 can map the following core C++ features to Python:
 ## Goodies
 In addition to the core functionality, pybind11 provides some extra goodies:
 
-- Python 2.7, 3.5+, and PyPy 7.3 are supported with an implementation-agnostic
+- Python 2.7, 3.5+, and PyPy (tested on 7.3) are supported with an implementation-agnostic
   interface.
 
 - It is possible to bind C++11 lambda functions with captured variables. The