Improve the Commit indexer xml doc

[nulltoken]

It currently states

/// <summary>
/// Gets the <see cref="TreeEntry"/> pointed at by the <paramref name="relativePath"/> in the <see cref="Tree"/>.
/// </summary>
/// <param name="relativePath">The relative path to the <see cref="TreeEntry"/> from the <see cref="Commit"/> working directory.</param>
/// <returns><c>null</c> if nothing has been found, the <see cref="TreeEntry"/> otherwise.</returns>

• relativePath usage is misleading. Maybe just path?
• working directory makes no sense from a Commit standpoint. Maybe just root?

[carlosmn]

Naming it "path" and changing the comment to something like

Path to the TreeEntry from the root tree

or

Path to the TreeEntry from the tree in this commit

should cover both situations ("root tree" and "tree in this commit" are equivalent concepts).

[nulltoken]

Path to the TreeEntry from the tree in this commit

👍