bip343: change status from deployed to closed (#2187)

* Update bip-0343.mediawiki

As a co-author I would like to move this BIP's status to Closed due to its current irrelevance and lack of any known deployments on the network. 

If I could I would delete it fully, or better yet go back in time to prevent it from being written.

* bip343: Fix table entry for move to Closed

* bip343: Record Close reason

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Co-authored-by: Murch <murch@murch.one>

README.mediawiki

@@ -1184,13 +1184,13 @@ users (see also: [https://en.bitcoin.it/wiki/Economic_majority economic majority
 | Pieter Wuille, Jonas Nick, Anthony Towns
 | Specification
 | Deployed
-|- style="background-color: #cfffcf"
+|- style="background-color: #ffcfcf"
 | [[bip-0343.mediawiki|343]]
 | Consensus (soft fork)
 | Mandatory activation of taproot deployment
 | Shinobius, Michael Folkson
 | Specification
-| Deployed
+| Closed
 |- style="background-color: #ffcfcf"
 | [[bip-0345.mediawiki|345]]
 | Consensus (soft fork)