fix: add summary to schemas where description has html

[sstrigler]

Fixes https://emqx.atlassian.net/browse/EMQX-8982

PR Checklist

Please convert it to a draft if any of the following conditions are not met. Reviewers may skip over until all the items are checked:

• [-] Added tests for the changes
• [-] Changed lines covered in coverage report
• Change log has been added to changes/{ce,ee}/(feat|perf|fix)-<PR-id>.en.md and .zh.md files
• For internal contributor: there is a jira ticket to track this change
• If there should be document changes, a PR to emqx-docs.git is sent, or a jira ticket is created to follow up
• Schema changes are backward compatible

Checklist for CI (.github/workflows) changes

• [-] If changed package build workflow, pass this action (manual trigger)
• [-] Change log has been added to changes/ dir for user-facing artifacts update

[coveralls]

Pull Request Test Coverage Report for Build 4502457699

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 19 unchanged lines in 7 files lost coverage.
• Overall coverage increased (+0.07%) to 81.007%

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Files with Coverage Reduction	New Missed Lines	%
apps/emqx_gateway/src/mqttsn/emqx_sn_channel.erl	1	73.13%
apps/emqx/src/emqx_channel.erl	1	87.64%
apps/emqx/src/emqx_cm.erl	1	91.44%
apps/emqx/src/emqx_ws_connection.erl	1	79.4%
apps/emqx_resource/src/emqx_resource_buffer_worker.erl	2	91.46%
apps/emqx/src/emqx_flapping.erl	3	80.85%
apps/emqx/src/emqx_reason_codes.erl	10	88.97%

Totals
Change from base Build 4501388374:	0.07%
Covered Lines:	24883
Relevant Lines:	30717

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💛 - Coveralls