Improve README.

README.md

@@ -3312,11 +3312,14 @@ either [`socat`](https://www.kali.org/tools/socat/)
 or
 [`ncat`](https://nmap.org/ncat/), which is available as part of
 the `ncat` or `nmap` package in most package managers, and
-[`pandoc`](https://pandoc.org/).
-When only `pandoc` is available, the current note is rendered and
+[`pandoc`](https://pandoc.org/). When neither `socat` or `ncat` is
+available and the Bash version is 5.2 or higher, [`nb browse`](#browse)
+falls back to a pure Bash implementation that supports all features
+except for the Ace editor. If only `pandoc` is available,
+the current note is rendered and
 <a href="#-linking">[[wiki-style links]]</a>
 go to unrendered, original files.
-If only `socat` or `ncat` is available without `pandoc`,
+When `socat`,`ncat`, or Bash 5.2 is available without `pandoc`,
 files in plain text formats are rendered with the original markup unconverted.
 If neither `ncat`, `socat`, nor `pandoc` is available,
 [`nb browse`](#browse) falls back to the default behavior of [`nb show`](#show).

docs/index.markdown

@@ -3318,11 +3318,14 @@ either [`socat`](https://www.kali.org/tools/socat/)
 or
 [`ncat`](https://nmap.org/ncat/), which is available as part of
 the `ncat` or `nmap` package in most package managers, and
-[`pandoc`](https://pandoc.org/).
-When only `pandoc` is available, the current note is rendered and
+[`pandoc`](https://pandoc.org/). When neither `socat` or `ncat` is
+available and the Bash version is 5.2 or higher, [`nb browse`](#browse)
+falls back to a pure Bash implementation that supports all features
+except for the Ace editor. If only `pandoc` is available,
+the current note is rendered and
 <a href="#-linking">[[wiki-style links]]</a>
 go to unrendered, original files.
-If only `socat` or `ncat` is available without `pandoc`,
+When `socat`,`ncat`, or Bash 5.2 is available without `pandoc`,
 files in plain text formats are rendered with the original markup unconverted.
 If neither `ncat`, `socat`, nor `pandoc` is available,
 [`nb browse`](#browse) falls back to the default behavior of [`nb show`](#show).