HBASE-22226 Incorrect level for headings in asciidoc

[murtazahassan123]

Changes made and warnings are gone.

[Apache-HBase]

🎊 +1 overall

Vote	Subsystem	Runtime	Comment
0	reexec	22	Docker mode activated.
		_ Prechecks _
+1	@author	0	The patch does not contain any @author tags.
		_ master Compile Tests _
+1	mvninstall	257	master passed
0	refguide	434	branch has no errors when building the reference guide. See footer for rendered docs, which you should manually inspect.
		_ Patch Compile Tests _
+1	mvninstall	241	the patch passed
+1	whitespace	0	The patch has no whitespace issues.
0	refguide	435	patch has no errors when building the reference guide. See footer for rendered docs, which you should manually inspect.
		_ Other Tests _
+1	asflicense	15	The patch does not generate ASF License warnings.
		1486

Subsystem	Report/Notes
Docker	Client=17.05.0-ce Server=17.05.0-ce base: https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-244/1/artifact/out/Dockerfile
GITHUB PR	#244
Optional Tests	dupname asflicense refguide
uname	Linux 117dd2450f31 4.4.0-138-generic #164-Ubuntu SMP Tue Oct 2 17:16:02 UTC 2018 x86_64 GNU/Linux
Build tool	maven
Personality	/testptch/patchprocess/precommit/personality/provided.sh
git revision	master / cb32f4f
maven	version: Apache Maven 3.5.4 (1edded0938998edf8bf061f1ceb3cfdeccf443fe; 2018-06-17T18:33:14Z)
refguide	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-244/1/artifact/out/branch-site/book.html
refguide	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-244/1/artifact/out/patch-site/book.html
Max. process+thread count	76 (vs. ulimit of 10000)
modules	C: . U: .
Console output	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-244/1/console
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