Add perf triage for this week.

Author: Mark-Simulacrum

draft/2020-08-04-this-week-in-rust.md

@@ -111,8 +111,8 @@ If you are a Rust project owner and are looking for contributors, please submit
 
 ## Rust Compiler Performance Triage
 
-* [2020-07-28](https://github.com/rust-lang/rustc-perf/blob/master/triage/2020-07-28.md).
-  2 regressions, 1 improvement, none in rollups.
+* [2020-08-03](https://github.com/rust-lang/rustc-perf/blob/master/triage/2020-08-03.md).
+  8 regressions, 2 improvements, 1 of them on rollups. 1 outstanding nag from last week.
 
 ## Approved RFCs