Explain stencils more clearly

Author: savannahostrowski

peps/pep-0774.rst

@@ -15,13 +15,16 @@ flag on Linux and Mac and ``--experimental-jit`` on Windows. To build CPython wi
 the JIT enabled, users are required to have LLVM installed on their machine
 (initially, with LLVM 16 but more recently, with LLVM 19). LLVM is responsible
 for generating stencils that are essential to our copy-and-patch JIT (see :pep:`744`).
+These stencils are predefined, architecture-specific templates that are used 
+to generate machine code at runtime.
 
 This PEP proposes removing the LLVM build-time dependency for JIT-enabled builds
-by hosting the generated stencils in the CPython repository to simplify the
-contributor experience and address concerns raised at the Python Core Developer
-Sprint in September 2024. That said, there is a clear tradeoff to consider, as
-improved developer experience does come at the cost of increased repository
-size.
+by hosting the generated stencils in the CPython repository. This approach
+allows us to leverage the checked-in stencils for supported platforms at build
+time, simplifying the contributor experience and address concerns raised at the
+Python Core Developer Sprint in September 2024. That said, there is a clear
+tradeoff to consider, as improved developer experience does come at the cost of
+increased repository size.
 
 It is important to note that this PEP is not a proposal to accept or reject the
 JIT itself but rather to determine whether the build-time dependency on LLVM is