DYN-7675: add node help doc files for Trim boundary condition node

[aparajit-pratap]

Purpose

Add node help doc files for Trim boundary condition node
DYN-7675

Declarations

Check these if you believe they are true

• The codebase is in a better state after this PR
• Is documented according to the standards
• The level of testing this PR includes is appropriate
• User facing strings, if any, are extracted into *.resx files
• All tests pass using the self-service CI.
• Snapshot of UI changes, if any.
• Changes to the API follow Semantic Versioning and are documented in the API Changes document.
• This PR modifies some build requirements and the readme is updated
• This PR contains no files larger than 50 MB

Release Notes

(FILL ME IN) Brief description of the fix / enhancement. Use N/A to indicate that the changes in this pull request do not apply to Release Notes. Mandatory section

Reviewers

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FYIs

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[github-actions]

See the ticket for this pull request: https://jira.autodesk.com/browse/DYN-7675

[zeusongit]

/cherrypick

[github-actions]

Successfully created backport PR for RC3.5.0_master:

• [Cherry-pick] DYN-7675: add node help doc files for Trim boundary condition node #15999