update metamask in docs and demo, yarn docs

Author: leightkt

docs/package.json

@@ -72,7 +72,7 @@
     "@web3-onboard/keystone": "^2.3.7",
     "@web3-onboard/ledger": "^2.6.0",
     "@web3-onboard/magic": "^2.1.7",
-    "@web3-onboard/metamask": "^2.0.5",
+    "@web3-onboard/metamask": "^2.0.6-alpha.1",
     "@web3-onboard/mew-wallet": "^2.0.4",
     "@web3-onboard/phantom": "^2.0.3",
     "@web3-onboard/portis": "^2.1.7",