Add docs

app/scripts/README-TXT-EXPORT.md

@@ -5,13 +5,23 @@ This script exports the article to a simple text format suitable for book publis
 ## Usage
 
 ```bash
-npm run export:txt
+yarn export:txt
 ```
 
 Or with custom filename:
 
 ```bash
-node scripts/export-txt.mjs --filename=my-article
+yarn export:txt -- --filename=my-article
+```
+
+By default, code blocks inside `<c>...</c>` are hard-wrapped to 80 characters per line. You can disable or configure this:
+
+```bash
+# Disable wrapping
+yarn export:txt -- --wrap-code=false
+
+# Change wrap width
+yarn export:txt -- --code-width=100
 ```
 
 ## Output
@@ -65,7 +75,7 @@ Example:
 ```
 Example:
 ```
-Use the <ic>npm install</ic> command to install dependencies.
+Use the <ic>yarn install</ic> command to install dependencies.
 ```
 
 #### LaTeX Formulas