Filter supportmd for markdownlinkcheck (#278)

.mega-linter.yml

@@ -16,3 +16,4 @@ POWERSHELL_POWERSHELL_FILTER_REGEX_EXCLUDE: (.*/Generators/templates/)
 JSON_JSONLINT_FILTER_REGEX_EXCLUDE: (.vscode/)
 BICEP_BICEP_LINTER_ARGUMENTS: --stdout
 JAVASCRIPT_PRETTIER_ARGUMENTS: --check
+MARKDOWN_MARKDOWN_LINK_CHECK_FILTER_REGEX_EXCLUDE: (SUPPORT.md)