[llvm] [SandboxIR] Add more Instruction member functions (PR #98588)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

The README.md states `LLVM's documentation is written in reStructuredText, a lightweight
plaintext markup language (file extension `.rst`). `

https://github.com/llvm/llvm-project/pull/98588