git: openjdk/leyden: premain: Improved benchmarks docs; added "make compare_premain_builds"

[duke]

Changeset: 12ab8469
Author:    iklam <ilam3388 at gmail.com>
Date:      2024-04-25 21:24:12 +0000
URL:       https://git.openjdk.org/leyden/commit/12ab8469c6a59fc86d61e9e099e3f3e4e2ddfc3b

Improved benchmarks docs; added "make compare_premain_builds"

! test/hotspot/jtreg/premain/README.md
+ test/hotspot/jtreg/premain/lib/Bench.gmk
! test/hotspot/jtreg/premain/lib/DemoSupport.gmk
! test/hotspot/jtreg/premain/lib/GithubMDChart.java
! test/hotspot/jtreg/premain/spring-petclinic/Makefile