Update CONTRIBUTORS.md

Author: guoyuanplct

CONTRIBUTORS.md

@@ -250,7 +250,14 @@ In chronological order:
 
 * Ye Tao <ye.tao@arm.com>
   * [2025-02-03] Optimize SBGEMM kernel on NEOVERSEV1
-  * [2025-02-27] Add sbgemv_n_neon kernel
+  * [2025-02-27] Add sbgemv_n_neon kernel2
 
 * Abhishek Kumar <https://github.com/abhishek-iitmadras>
-  * [2025-04-22] Optimise dot kernel for NEOVERSE V1
+  * [2025-04-22] Optimise dot kernel for NEOVERSE V1
+
+* Guoyuan Li <https://github.com/guoyuanplct>
+  * [2025-04-11] Optimise gemv kernel for RISCV64_ZVL256B
+  * [2025-05-01] Optimise zgemv kernel for RISCV64_ZVL256B
+  * [2025-05-17] Optimise omatcopy/zomatcopy kernel for RISCV64_ZVL256B
+  * [2025-05-29] Optimise axpby kernel for RISCV64_ZVL256B
+  * [2025-06-05] Optimise hbmv kernel for RISCV64_ZVL256B