Minor editorial suggestions from spec read through

[zimeon]

It has been a long time since I've read the whole spec through in one. With fresh eyes I noticed the following:

• In https://ocfl.io/1.1/spec/#digests, missing word: "The second role that digests play is [to] provide for fixity checks to determine whether a file has become corrupt, through hardware degradation or accident for example."
• In https://ocfl.io/1.1/spec/#inventory, can improve clarity: "Implementations that target [storage] systems using other separators will need to translate paths appropriately."
• In https://ocfl.io/1.1/spec/#inventory-structure can improve clarity: "This MUST be the algorithm used in the manifest and state blocks[. See], see the section on Digests for more information about algorithms."
• In https://ocfl.io/1.1/spec/#version can improve clarity and better align with : "Logical paths present the structure of an [object's content]OCFL Object at a given version."
• In https://ocfl.io/1.1/spec/#fixity we can be more consistent. We don't usually include section number unless we say section: "The value of the fixity block for a particular digest algorithm MUST follow the structure of the 3.5.2 Manifest block; "