Allow snippets in parameter definitions

[vors]

Steps to reproduce

There is a legitimate use of snippets in parameter descriptions.
I.e. https://github.com/PowerShell/PowerShell-Docs/blob/a3fbff254eb48ce1fcb94995a07a6052b1841c78/reference/5.1/Microsoft.PowerShell.Utility/ConvertFrom-String.md#-templatefile

Expected behavior

We should be able to compile it

Actual behavior

Exception calling "NodeModelToMamlModel" with "1" argument(s):
"F:\dev\PowerShell-Docs\reference\5.0\Microsoft.PowerShell.Utility\ConvertFrom-String.md:346:(1308) '```
{Name*:David Chew}
{City:Redmond}, {State:...'
 Invalid yaml: unknown key {Name*"
At F:\dev\platyPS\out\platyPS\platyPS.psm1:1224 char:9
+         $maml = $t.NodeModelToMamlModel($model)
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : HelpSchemaException

Environment data

0.7.3

[vors]

Fixed per #60a3a40