HADOOP-19407: Update 3.4.1 docs landing page to highlight changes shipped in the release.

[cnauroth]

Description of PR

The landing page for the 3.4.1 docs mostly lists changes that already shipped in 3.4.0. Update this to highlight 3.4.1 changes.

How was this patch tested?

mvn site site:stage -Preleasedocs,docs -DstagingDirectory=/tmp/hadoop-site

I loaded the resulting site build in my browser, verified the changes were present, and all links went to the correct issues.

I haven't tried in the hadoop-site repo yet. I'll do that next if this gets approved.

For code changes:

• Does the title or this PR starts with the corresponding JIRA issue id (e.g. 'HADOOP-17799. Your PR title ...')?
• Object storage: have the integration tests been executed and the endpoint declared according to the connector-specific documentation?
• If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under ASF 2.0?
• If applicable, have you updated the LICENSE, LICENSE-binary, NOTICE-binary files?

[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 21s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell was not available.
+0 🆗	detsecrets	0m 0s		detect-secrets was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
			_ trunk Compile Tests _
+1 💚	mvninstall	23m 40s		trunk passed
+1 💚	mvnsite	0m 17s		trunk passed
+1 💚	shadedclient	43m 14s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 10s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	mvnsite	0m 11s		the patch passed
+1 💚	shadedclient	19m 16s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	asflicense	0m 25s		The patch does not generate ASF License warnings.
		64m 19s

Subsystem	Report/Notes
Docker	ClientAPI=1.47 ServerAPI=1.47 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7338/1/artifact/out/Dockerfile
GITHUB PR	#7338
Optional Tests	dupname asflicense mvnsite codespell detsecrets
uname	Linux e24e2c4a3bb3 5.15.0-130-generic #140-Ubuntu SMP Wed Dec 18 17:59:53 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 35ed483
Max. process+thread count	549 (vs. ulimit of 5500)
modules	C: hadoop-project U: hadoop-project
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7338/1/console
versions	git=2.25.1 maven=3.6.3
Powered by	Apache Yetus 0.14.0 https://yetus.apache.org

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[cnauroth]

@slfan1989 , thanks for the approval! I committed this to trunk, branch-3.4 and branch-3.4.1.