Update src/doc/rustc/src/profile-guided-optimization.md

Co-authored-by: Jakub Beránek <[email protected]>

Author: meysam81

src/doc/rustc/src/profile-guided-optimization.md

@@ -165,5 +165,5 @@ cargo pgo optimize
 These steps will do the following just as before:
 
 1. Build an instrumented binary from the source code.
-2. Use the instrumentation in the binary when running it for the first time.
+2. Run the instrumented binary to gather PGO profiles.
 3. Use the instrumentation results from the last step to create an optimized binary.