array/list.distinct and fixes to seq.distinct

[liboz]

related to #184

[orcabot]

Hi! I'm your friendly content validation bot. For this PR to be labeled as ready-to-merge, you'll need at least 2 comments from our designated community approvers containing the magic phrase LGTM (Looks good to me also works, for those of us that are really verbose).

@dend @KevinRansom @cartermp @thedanfernandez @dsyme - please validate this PR.

[orcabot]

• docs/conceptual/collections.list-module-[fsharp].md - Article contains URLs. Make sure that non-Microsoft URLs are using the aka.ms shortener.
• docs/conceptual/array.distinct['t]-function-[fsharp].md - Article contains URLs. Make sure that non-Microsoft URLs are using the aka.ms shortener.
• docs/conceptual/collections.array-module-[fsharp].md - Article contains URLs. Make sure that non-Microsoft URLs are using the aka.ms shortener.
• docs/conceptual/seq.distinct['t]-function-[fsharp].md - Article contains URLs. Make sure that non-Microsoft URLs are using the aka.ms shortener.
• docs/conceptual/list.distinct['t]-function-[fsharp].md - Article contains URLs. Make sure that non-Microsoft URLs are using the aka.ms shortener.

[dend]

Overall LGTM, but want someone from the F# team to go over the accuracy. @KevinRansom @cartermp

[cartermp]

LGTM. Thanks, @liboz!