chore: update readme/doc

1 files changed, 36 insertions, 10 deletions

diff --git a/README.md b/README.md
index 7fa10a8..7f5abd6 100644
--- a/README.md
+++ b/README.md
@@ -108,9 +108,44 @@ vim.api.nvim_create_autocmd("BufWritePre", {
 
 See `:help muwiki-autocmd` for more examples.
 
+## Configuration Options
+
+### text_extensions
+
+Controls which file extensions open directly in Neovim when using `file://` links. Files with matching extensions bypass `xdg-open` and open in a Neovim buffer instead.
+
+**Default:** `{}` (empty - all file:// links open with xdg-open)
+
+**Format:** Accepts extensions with or without leading dot (e.g., `'txt'` or `'.txt'`)
+
+**Example:**
+```lua
+muwiki.setup({
+  dirs = {{ name = 'default', path = '~/wiki' }},
+  -- Open these file types directly in Neovim
+  text_extensions = { 'txt', 'md', 'png' },
+})
+```
+
+This allows you to open binary files like PNG images directly in Neovim for hex editing or inspection instead of xdg-open.
+
+**Behavior:**
+
+**xdg-open:**
+
+- `[Link](https://example.com)`
+- `[Link](file:///path/to/file.mp4)`
+
+**Neovim:**
+
+- `[Link](file://../relative/path/to/image.png)` → matches text_extensions
+- `[Link](/absolute/path/to/file.txt)`
+- `[Link](../relative/path/to/file.txt)`
+- `[Link](SomePage.md)`
+
 ## Available Actions
 
-- `open_link()` - Open link under cursor (wiki→nvim, web/files→xdg-open)
+- `open_link()` - Open link under cursor
 - `next_link()` - Jump to next markdown link
 - `prev_link()` - Jump to previous markdown link
 - `create_link()` - Create link from visual selection
@@ -120,15 +155,6 @@ See `:help muwiki-autocmd` for more examples.
 
 See `:help muwiki-api` for detailed function documentation.
 
-## Link Format
-
-```text
-[Wiki page](page.md)
-[Website](https://example.com)
-[Relative path](file://../document.pdf)
-[Absolute path](file:///tmp/image.png)
-```
-
 ## Recommended Plugins
 
 These plugins work well with muwiki.nvim: