[readme] Fix java example backlinks #3028

Job	Run time
photon-build-all	4m 32s
photonclient-build	58s
photonclient-check-lint	44s
Build Examples	4m 52s
Photonlib - Build Docker - Athena	8m 23s
Photonlib - Build Host - Win64	8m 53s
wpiformat	20s
Photonlib - Build Docker - Raspbian	13m 43s
photonserver-build-offline-docs	1m 34s
Photonlib - Build Host - Linux	5m 39s
Photonlib - Build Docker - Aarch64	13m 1s
photonserver-check-lint	49s
Build fat JAR - Win64	2m 56s
Build fat JAR - macOS	3m 10s
Build fat JAR - Linux	2m 10s
Build fat JAR - macOSArm	3m 5s
Build fat JAR - LinuxArm32	1m 41s
Build fat JAR - LinuxArm64	2m 18s
Build image - ${{ matrix.image_url }}	0s
photon-release	0s
	1h 18m 48s

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