Improve wording on unreachable sections based on EIP-4750 (#123)

spec/eof.md

@@ -291,7 +291,7 @@ The following instructions are introduced in EOF code:
 - `RETURNCONTRACT` the subcontainer pointed to `deploy_container_index` must be a "runtime" subcontainer, that is, it *must not* contain a `RETURNCONTRACT` instruction.
 - `DATALOADN`'s `immediate + 32` must be within `pre_deploy_data_size` (see [Data Section Lifecycle](#data-section-lifecycle))
      - the part of the data section which exceeds these bounds (the `dynamic_aux_data` portion) needs to be accessed using `DATALOAD` or `DATACOPY`
-- no unreachable sections are allowed, i.e. every section is referenced by at least one non-recursive `CALLF` or `JUMPF`, and section 0 is implicitly reachable.
+- no unreachable code sections are allowed, i.e. every code section can be reached from the 0th code section with a series of CALLF / JUMPF instructions, and section 0 is implicitly reachable.
 - it is an error for a container to contain both `RETURNCONTRACT` and either of `RETURN` or `STOP`.
 - it is an error for a subcontainer to never be referenced in code sections of its parent container
 - for terminology purposes, the following concepts are defined: