[TEZ-4439] Update the protobuf documentation in TEZ codebase

[amanraj2520]

[TEZ-4439] Update the protobuf documentation in TEZ codebase.

Link to the issue : https://issues.apache.org/jira/browse/TEZ-4439

The protobuf dependency was upgraded from 2.5.0 to 3.19.4 as tracked in this issue : https://issues.apache.org/jira/browse/TEZ-4363. But there were certain mentions of protobuf 2.5.0 in the documentations of protobuf within the TEZ codebase. Raised this PR to update those documentations.

[tez-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Comment
+0 🆗	reexec	32m 44s	Docker mode activated.
		_ Prechecks _
+1 💚	dupname	0m 0s	No case conflicting files found.
+1 💚	@author	0m 0s	The patch does not contain any @author tags.
		_ master Compile Tests _
+1 💚	mvninstall	16m 58s	master passed
+1 💚	mvnsite	0m 43s	master passed
		_ Patch Compile Tests _
+1 💚	mvninstall	0m 10s	the patch passed
-1 ❌	markdownlint	0m 4s	The patch generated 1 new + 116 unchanged - 0 fixed = 117 total (was 116)
+1 💚	mvnsite	0m 9s	the patch passed
+1 💚	whitespace	0m 0s	The patch has no whitespace issues.
		_ Other Tests _
+1 💚	asflicense	0m 19s	The patch does not generate ASF License warnings.
		51m 50s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/tez-multibranch/job/PR-233/1/artifact/out/Dockerfile
GITHUB PR	#233
JIRA Issue	TEZ-4439
Optional Tests	dupname asflicense markdownlint mvnsite
uname	Linux 2275f681f3b0 4.15.0-112-generic #113-Ubuntu SMP Thu Jul 9 23:41:39 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	personality/tez.sh
git revision	master / c386865
markdownlint	https://ci-hadoop.apache.org/job/tez-multibranch/job/PR-233/1/artifact/out/diff-patch-markdownlint.txt
Max. process+thread count	77 (vs. ulimit of 5500)
modules	C: docs U: docs
Console output	https://ci-hadoop.apache.org/job/tez-multibranch/job/PR-233/1/console
versions	git=2.25.1 maven=3.6.3 markdownlint=0.23.2
Powered by	Apache Yetus 0.12.0 https://yetus.apache.org

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[abstractdog]

thanks @amanraj2520 , could you please check INSTALL.md (in root folder) for the same?

[amanraj2520]

@abstractdog The INSTALL.md folder is symbolic linked to docs/src/site/markdown/install.md where I have made the changes.

[amanraj2520]

@abstractdog Can you please let me know if you have any suggestions or are we good to merge this?

[abstractdog]

merged to master, thanks a lot @amanraj2520 for taking care of docs