Add DETECT2 to inst_list

[KathrynBaker]

Description of work

Added DETECT2 as an entry for the inst list

To test

IBEX#9037

Acceptance criteria

• There is now an entry for DETECT2

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Code Review

• Is the code of an acceptable quality?
• Has the author taken into account the multi-threaded nature of the code?
• Have the changes been recorded appropriately in a PR for release notes?
• Has the manual system tests spreadsheet been updated?

Functional Tests

• Do changes function as described? Add comments below that describe the tests performed.

Final steps

• Reviewer has updated the submodule in the main EPICS repo? See Reviewing work for the subModules of EPICS in the Git workflow page for details.
• Reviewer has merged the associated PR for the release notes