RFR: 7903658 Document build/make.sh [v2]

[Ludvig Janiuk]

> Add a note in building.md about build/make.sh, explaning that you can use it to rebuild faster.

Ludvig Janiuk has updated the pull request incrementally with one additional commit since the last revision:

  Update building.md

-------------

Changes:
  - all: https://git.openjdk.org/jtreg/pull/182/files
  - new: https://git.openjdk.org/jtreg/pull/182/files/85ee2590..8577285d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jtreg&pr=182&range=01
 - incr: https://webrevs.openjdk.org/?repo=jtreg&pr=182&range=00-01

  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jtreg/pull/182.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/182/head:pull/182

PR: https://git.openjdk.org/jtreg/pull/182