RFR: 8318693: Fix rendering for code blocks nested under list items in building.md

[Zixian Cai]

Currently, code blocks under list items are rendered in a single line, which is 
difficult to read and copy.
For example, see below from 
https://htmlpreview.github.io/?https://raw.githubusercontent.com/openjdk/jdk/master/doc/building.html#building-for-risc-v
 
![Screenshot 2023-10-24 at 13 46 
03](https://github.com/openjdk/jdk/assets/2891235/fc9f1472-74a8-451f-b797-66973b4ec81c)

After fix
![Screenshot 2023-10-24 at 13 47 
49](https://github.com/openjdk/jdk/assets/2891235/b11027c1-bbdc-47c2-b209-976b86865fcc)

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

Commit messages:
 - Remove trailing whitespace
 - Fix rendering for code blocks nested under list item in building.md

Changes: https://git.openjdk.org/jdk/pull/16332/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16332&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318693
  Stats: 83 lines in 2 files changed: 39 ins; 5 del; 39 mod
  Patch: https://git.openjdk.org/jdk/pull/16332.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16332/head:pull/16332

PR: https://git.openjdk.org/jdk/pull/16332