Update 1.8.2502 release notes (microsoft#7147)

An internal fix has changed the way PDB files are packaged on release.
This change is worth noting in the release notes for 1.8.2502.

Author: bob80905

docs/ReleaseNotes.md

@@ -19,10 +19,15 @@ The included licenses apply to the following files:
 
 ### Version 1.8.2502
 
-- The incomplete WaveMatrix implementation has been removed.
-- DXIL Validator Hash is open sourced.
-- DXIL container validation for PSV0 part allows any content ordering inside string and semantic index tables.
-- The and() and or() intrinsics will now accept non-integer parameters by casting them to bools.
+This cumulative release contains numerous bug fixes and stability improvements.
+
+Here are some highlights:
+
+- The incomplete WaveMatrix implementation has been removed. [#6807](https://github.com/microsoft/DirectXShaderCompiler/pull/6807)
+- DXIL Validator Hash is open sourced. [#6846](https://github.com/microsoft/DirectXShaderCompiler/pull/6846)
+- DXIL container validation for PSV0 part allows any content ordering inside string and semantic index tables. [#6859](https://github.com/microsoft/DirectXShaderCompiler/pull/6859)
+- The and() and or() intrinsics will now accept non-integer parameters by casting them to bools. [#7060](https://github.com/microsoft/DirectXShaderCompiler/pull/7060)
+- Released executables will now expect the filenames associated with the released pdbs. Instead of expecting `dxc_full.pdb`, `dxc.exe` will now expect `dxc.pdb`.
 
 ### Version 1.8.2407