Fix backtick mistakes

Author: zklaus

peps/pep-0790.rst

@@ -378,17 +378,17 @@ found in `Add abi_features to sys
 <https://github.com/zklaus/cpython/pull/1>`__.
 
 The reference implementation for the environment markers is available in a fork
-of the `packaging` library at `Environment markers for ABI features
+of the ``packaging`` library at `Environment markers for ABI features
 <https://github.com/zklaus/packaging/pull/1>`__.
 
 `A demonstration package <https://github.com/zklaus/env-marker-example>`__ is
 also available.
 
-Since `pip` uses a vendored copy of `packaging` internally, we also provide
+Since ``pip`` uses a vendored copy of ``packaging`` internally, we also provide
 `a patched version of pip
 <https://github.com/zklaus/pip/tree/env-marker-free-threading>`__, which is
-based on pypa/pip:main with the vendored `packaging` replaced by the reference
-implementation linked above.
+based on pypa/pip:main with the vendored ``packaging`` replaced by the
+reference implementation linked above.
 
 Rejected Ideas
 ==============
@@ -425,7 +425,7 @@ to include them.
 
 Other Tooling
 -------------
-The reference implementation is based on the `packaging` library and `pip`.
+The reference implementation is based on the ``packaging`` library and ``pip``.
 We have confirmed that this allows for building and installing packages with
 several build backends.
 It is possible that other tools should be added to the reference