add isulad maillist in website

Signed-off-by: Ncaihaomin <c00416947@china.huawei.com>

content/en/maillist/isulad.md

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+listname = "iSulad"
+emailaddress = "isulad@openeuler.org"
+description = "Mail list for development on iSulad."
+websitelink = "https://mailweb.openeuler.org/postorius/lists/isulad.openeuler.org"
+archivelink = "https://mailweb.openeuler.org/hyperkitty/list/isulad@openeuler.org"
+weight =  12
+
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+

content/zh/maillist/isulad.md

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+listname = "iSulad"
+emailaddress = "isulad@openeuler.org"
+description = "iSulad项目邮件讨论组。"
+websitelink = "https://mailweb.openeuler.org/postorius/lists/isulad.openeuler.org"
+archivelink = "https://mailweb.openeuler.org/hyperkitty/list/isulad@openeuler.org"
+weight =  12
+
++++