[Bug] Inheritdoc Rendering Isssue in Sections

[StefanGreve]

Describe the bug
I have noticed that every time when I use a <inheritdoc> within a <remarks> section, the rendered output looks off. I will give an example for how to reproduce this problem with a remarks reference, but there are also other cases where inheritdoc fails to render the output properly in DocFx (cf. Context, Exhibit 2).

To Reproduce
Steps to reproduce the behavior:

1. Decorate a function Foo with a doc string, and include a <remarks> section

/// <summary>
///    Foo.
/// </summary>
/// <remarks>
///    Hello <c>World!</c>.
/// </remarks>
public void Foo() => throw new NotImplementedException();

2. Reference the remark from Foo in Bar:

/// <summary>
///    Bar.
/// </summary>
/// <remarks>
///    <inheritdoc cref="Foo" path="/remarks" />
/// </remarks>
public void Bar() => throw new NotImplementedException();

Expected behavior

The output should look like this:

Remarks

Hello World!.

---

But instead, it comes out like this:

Remarks

<remarks>
Hello <c>World!</c>.

Context (please complete the following information):

• OS: Windows
• Docfx version: 2.78.4

Additional context
Here are some screen shots from a real world application:

Exhibit 1

Exhibit 2

where I used something like

    /// <param name="eventLogOptions">
    ///     <inheritdoc cref="EventLogOptions" path="/summary"/>
    /// </param>

(Edit: Fixed typos (</remarks>).

[filzrev]

It can reproduced on following test code (Original example code lacks </remarks> closing tag)

public class TestClass
{
    /// <summary>
    ///     Foo.
    /// </summary>
    /// <remarks>
    ///     Hello <c>World!</c>.
    /// </remarks>
    public void Foo() => throw new NotImplementedException();

    /// <summary>
    ///     Bar.
    /// </summary>
    /// <remarks>
    ///     <inheritdoc cref="Foo" path="/remarks" />
    /// </remarks>
    public void Bar() => throw new NotImplementedException();
}

And Following xml tag is extracted by GetFullXmlFragment Roslyn API (It's not publicly exposed).

<member name="M:BuildFromCSharpSourceCode.AAA.Bar">
    <summary>
        Bar.
    </summary>
    <remarks>
        <remarks>
        Hello <c>World!</c>.
    </remarks>
    </remarks>
</member>

It seems duplicated <remark></remarks> tags and mismatched indents causing reported issue.