HADOOP-19814: Update 3.5.0 docs landing page to highlight changes shipped in the release.

[cnauroth]

Description of PR

This updates the docs landing page for 3.5.0 to summarize some of the major contributions at a high level.

How was this patch tested?

mvn site site:stage -Preleasedocs,docs -DstagingDirectory=/tmp/hadoop-site and browse the generated site.

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?

AI Tooling

If an AI tool was used:

• The PR includes the phrase "Contains content generated by "
  where is the name of the AI tool used.
• My use of AI contributions follows the ASF legal policy
  https://www.apache.org/legal/generative-tooling.html

[cnauroth]

@ajfabbri , @ayushtkn or @mukund-thakur , can I please get your review on this small docs change for 3.5.0? Thank you.

[ayushtkn]

LGTM

[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 22s		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	27m 35s		trunk passed
+1 💚	mvnsite	0m 31s		trunk passed
+1 💚	shadedclient	43m 43s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 11s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	mvnsite	0m 12s		the patch passed
+1 💚	shadedclient	14m 34s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	asflicense	0m 23s		The patch does not generate ASF License warnings.
		60m 26s

Subsystem	Report/Notes
Docker	ClientAPI=1.54 ServerAPI=1.54 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8407/2/artifact/out/Dockerfile
GITHUB PR	#8407
Optional Tests	dupname asflicense mvnsite codespell detsecrets
uname	Linux 6b30a2c7afd7 5.15.0-173-generic #183-Ubuntu SMP Fri Mar 6 13:29:34 UTC 2026 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 37ab517
Max. process+thread count	617 (vs. ulimit of 10000)
modules	C: hadoop-project U: hadoop-project
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8407/2/console
versions	git=2.43.0 maven=3.9.11
Powered by	Apache Yetus 0.14.1 https://yetus.apache.org

This message was automatically generated.

[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 52s		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	48m 46s		trunk passed
+1 💚	mvnsite	0m 46s		trunk passed
+1 💚	shadedclient	83m 14s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 14s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	mvnsite	0m 17s		the patch passed
+1 💚	shadedclient	32m 22s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	asflicense	0m 34s		The patch does not generate ASF License warnings.
		119m 12s

Subsystem	Report/Notes
Docker	ClientAPI=1.54 ServerAPI=1.54 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8407/1/artifact/out/Dockerfile
GITHUB PR	#8407
Optional Tests	dupname asflicense mvnsite codespell detsecrets
uname	Linux c0173d98ac46 5.15.0-173-generic #183-Ubuntu SMP Fri Mar 6 13:29:34 UTC 2026 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 37ab517
Max. process+thread count	575 (vs. ulimit of 10000)
modules	C: hadoop-project U: hadoop-project
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8407/1/console
versions	git=2.43.0 maven=3.9.11
Powered by	Apache Yetus 0.14.1 https://yetus.apache.org

This message was automatically generated.

[cnauroth]

Pushed to trunk and branch-3.5. Thanks for the review @ayushtkn .