Fix SA1629 "... should end with a period" in generated xml docs

Also, <remarks><para>... is generated like:

/// <para><see href="https://docs.microsoft.com/windows/win32/api/iphlpapi/nf-iphlpapi-sendarp">Learn more about this API from docs.microsoft.com.</see></para>

while the end of <summary> is generated as:

/// <para><see href="https://docs.microsoft.com/windows/win32/api/iphlpapi/nf-iphlpapi-sendarp#parameters">Read more on docs.microsoft.com</see>.</para>

thus, beeing SA1629 compliant.

src/Microsoft.Windows.CsWin32/Generator.cs

@@ -2020,7 +2020,7 @@ private T AddApiDocumentation<T>(string api, T memberDeclaration)
                     else if (docs.HelpLink is object)
                     {
                         docCommentsBuilder.AppendLine();
-                        docCommentsBuilder.AppendLine($@"/// <para><see href=""{docs.HelpLink}"">Learn more about this API from docs.microsoft.com.</see></para>");
+                        docCommentsBuilder.AppendLine($@"/// <para><see href=""{docs.HelpLink}"">Learn more about this API from docs.microsoft.com</see>.</para>");
                         docCommentsBuilder.Append("/// ");
                     }