Typo

Co-authored-by: Joshua Nelson <joshua@yottadb.com>

src/appendix/code-index.md

@@ -20,7 +20,7 @@ Item            |  Kind    | Short description           | Chapter            |
 `ParseSess` | struct | This struct contains information about a parsing session | [The parser] | [compiler/rustc_session/src/parse/parse.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_session/parse/struct.ParseSess.html)
 `Query` | struct | Represents the result of query to the `Compiler` interface and allows stealing, borrowing, and returning the results of compiler passes. | [The Rustc Driver and Interface] | [compiler/rustc_interface/src/queries.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_interface/queries/struct.Query.html)
 `Rib` | struct | Represents a single scope of names | [Name resolution] | [compiler/rustc_resolve/src/lib.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_resolve/late/struct.Rib.html)
-`Session` | struct | The data associated with a compilation session | [The parser], [The Rustc Driver and Interface] | [compiler/rustc_middle/src/session/mod.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_session/struct.Session.html)
+`Session` | struct | The data associated with a compilation session | [The parser], [The Rustc Driver and Interface] | [compiler/rustc_session/src/session.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_session/struct.Session.html)
 `SourceFile` | struct | Part of the `SourceMap`. Maps AST nodes to their source code for a single source file. Was previously called FileMap | [The parser] | [compiler/rustc_span/src/lib.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.SourceFile.html)
 `SourceMap` | struct | Maps AST nodes to their source code. It is composed of `SourceFile`s. Was previously called CodeMap | [The parser] | [compiler/rustc_span/src/source_map.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/source_map/struct.SourceMap.html)
 `Span` | struct  | A location in the user's source code, used for error reporting primarily | [Emitting Diagnostics] | [compiler/rustc_span/src/span_encoding.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html)