Sync MediaTypeNames docs from dotnet/runtime

[antonfirsov]

This is a follow up on #9301 (comment): dotnet/runtime#92220 had some changes that did not make into the dotnet-api-docs repo in #9301.

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Issue Details

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This is a follow up on #9301 (comment): dotnet/runtime#92220 had some changes that did not make into the dotnet-api-docs repo in #9301.

Author:	antonfirsov
Assignees:	-
Labels:	area-System.Net, untriaged, Pri3
Milestone:	-

[rzikm]

This was fixed by #9313. The comments are now in sync.