SDK and Wasm methods are undocumented

[LauraLangdon]

Per https://threads.com/messages/fab16039-16b3-4549-80a5-63341dbf5b44?messageID=15871a03-1813-42d6-973e-abc6304deed7, we need to document the following methods:

From the SE2 SDK:

• return_result
• return_error
• log-msg
• graphql-query
• request-get-field
• request-set-field
• resp-set-header
• get-ffi-result
• add-ffi-var
• return-abort

From the Wasm module:

• run_e
• allocate
• deallocate
• _start

The Wasm module ones were beta-documented by the Wasm Labs team, and to get us going, @MacklinEngineering and I will beta-doc the rest in same style.