[readme] update coverage report in readme

Author: Clo91eaf

readme.md

@@ -37,7 +37,7 @@ It's build script is in `nix/gcd` folder, providing the below attributes:
 * [{tb,formal}-]rtl: SystemVerilog generated from the lowered MLIR bytecode
 * tb-dpi-lib: DPI library written in Rust for both Verilator and VCS
 * verilated[-trace]: C++ simulation executable and libaray generated by Verilator with/without `fst` waveform trace
-* vcs[-trace]: C simulation executable compiled by VCS with/without `fsdb` waveform trace
+* vcs[-trace]: C simulation executable compiled by VCS with/without `fsdb` waveform trace and `urgReport` (coverage report) would be generated under `gcd-sim-result/result/`
 * jg-fpv: Formal Property Verification report generated by JasperGold
 
 To get the corresponding output, developers can use: