docs: add documentation for org_adapt_indentation

DOCS.md

@@ -273,6 +273,16 @@ Possible values:
 * `true` - Enables indent mode on startup. Lines that follow headlines are indented to that headline level.
 * `false` - Disables indent mode on startup. All lines start from the first column.
 
+#### **org_adapt_indentation**
+
+*type*: `boolean`<br />
+*default value*: `true`<br />
+Possible values:
+* `true` - Converts indents to *Virtual* indents. The indents are only visual, they are not saved  to the file.
+* `false` - Use real indents, indentation as seen is what is saved to the file.
+
+This feature has no effect when enabled on Neovim verions < 0.10.0
+
 #### **org_src_window_setup**
 *type*: `string|function`<br />
 *default value*: "top 16new"<br />