Rename the output root directory in the render context.

src/context/render_context.rs

@@ -8,7 +8,7 @@ use crate::error::CustomError;
 pub(crate) struct RenderContext<'intermediate> {
     pub(crate) config: &'intermediate Config,
     // TODO: Perhaps rename to output_root_directory.
-    pub(crate) output_directory: &'intermediate Path,
+    pub(crate) output_root_directory: &'intermediate Path,
     pub(crate) output_file: &'intermediate Path,
 
     /// An optional string that gets added to IDs in HTML.
@@ -28,7 +28,7 @@ impl<'intermediate> RenderContext<'intermediate> {
     ) -> Result<RenderContext<'intermediate>, CustomError> {
         Ok(RenderContext {
             config,
-            output_directory,
+            output_root_directory: output_directory,
             output_file,
             id_addition,
         })