Add docs for mdx expressions

1 files changed, 33 insertions, 3 deletions

diff --git a/src/construct/mdx_expression_text.rs b/src/construct/mdx_expression_text.rs
index 8d061eb..53160a0 100644
--- a/src/construct/mdx_expression_text.rs
+++ b/src/construct/mdx_expression_text.rs
@@ -1,10 +1,40 @@
-//! To do.
+//! MDX expression (text) occurs in the [text][] content type.
+//!
+//! ## Grammar
+//!
+//! MDX expression (text) forms with the following BNF
+//! (<small>see [construct][crate::construct] for character groups</small>):
+//!
+//! ```bnf
+//! mdx_expression_text ::= mdx_expression
+//!
+//! ; See the `partial_mdx_expression` construct for the BNF of that part.
+//! ```
+//!
+//! See [`mdx_expression`][mdx_expression] for more info.
+//!
+//! ## Tokens
+//!
+//! *   [`MdxTextExpression`][Name::MdxTextExpression]
+//! *   see [`mdx_expression`][mdx_expression] for more
+//!
+//! ## Recommendation
+//!
+//! See [`mdx_expression`][mdx_expression] for recommendations.
+//!
+//! ## References
+//!
+//! *   [`syntax.js` in `micromark-extension-mdx-expression`](https://github.com/micromark/micromark-extension-mdx-expression/blob/main/packages/micromark-extension-mdx-expression/dev/lib/syntax.js)
+//! *   [`mdxjs.com`](https://mdxjs.com)
+//!
+//! [text]: crate::construct::text
+//! [mdx_expression]: crate::construct::partial_mdx_expression
 
 use crate::event::Name;
 use crate::state::{Name as StateName, State};
 use crate::tokenizer::Tokenizer;
 
-/// Start of MDX: expression (text).
+/// Start of an MDX expression (text).
 ///
 /// ```markdown
 /// > | a {Math.PI} c
@@ -22,7 +52,7 @@ pub fn start(tokenizer: &mut Tokenizer) -> State {
     }
 }
 
-/// After an MDX expression (text) tag.
+/// After expression.
 ///
 /// ```markdown
 /// > | a {Math.PI} c