docs: fix some release notes snippet typos

commit 6a8330af598753d5982a37933beeac2d6b565386: hpp was clearly meant
and used several times, just not in the release notes themelves.

commit a75ced6d50a3d479eda6dcdc9c3482493f2161f0: C/C++ "what"? We
mention the std in the commit, but not in the text of the release notes.

docs/markdown/snippets/rust-bindgen-cpp.md

@@ -1,6 +1,6 @@
 ## Bindgen will now use Meson's hueristic for what is a C++ header
 
-Bindgen natively assumes that a file with the extension `.cpp` is a C++ header,
+Bindgen natively assumes that a file with the extension `.hpp` is a C++ header,
 but that everything else is a C header. Meson has a whole list of extensions it
 considers to be C++, and now will automatically look for those extensions and
 set bindgen to treat those as C++

docs/markdown/snippets/rust-bindgen-std.md

@@ -1,3 +1,3 @@
-## Bindgen now uses the same C/C++ as the project as a whole
+## Bindgen now uses the same C/C++ std as the project as a whole
 
 Which is very important for C++ bindings.