git: openjdk/guide: Add notes on avoiding spurious introduction of labels.

[Jesper Wilhelmsson]

Changeset: 901eeba3
Author:    Stuart Marks <smarks at openjdk.org>
Committer: Jesper Wilhelmsson <jwilhelm at openjdk.org>
Date:      2020-10-19 17:33:44 +0000
URL:       https://git.openjdk.java.net/guide/commit/901eeba3

Add notes on avoiding spurious introduction of labels.

Reviewed-by: iignatyev, iris

! src/index.md