Fixes from PR feedback

This contains fixes suggested by Henrik as feedback from the initial PR,
including updating and correcting the Eshell module README, and few
tweaks to the module configuration, and properly pinning
eshell-did-you-mean.

modules/term/eshell/README.org

@@ -1,9 +1,17 @@
 #+TITLE:   term/eshell
-#+DATE:    April 17, 2020
-#+SINCE:   {replace with next tagged release version}
+#+DATE:    May 18, 2020
+#+SINCE:   v2.0
 #+STARTUP: inlineimages nofold
 
 * Table of Contents :TOC_3:noexport:
+- [[#description][Description]]
+  - [[#maintainers][Maintainers]]
+  - [[#module-flags][Module Flags]]
+  - [[#plugins][Plugins]]
+- [[#prerequisites][Prerequisites]]
+- [[#features][Features]]
+- [[#configuration][Configuration]]
+- [[#troubleshooting][Troubleshooting]]
 
 * Description
 This module provides additional features for the built-in [[https://www.gnu.org/software/emacs/manual/html_mono/eshell.html][Emacs Shell]]
@@ -30,7 +38,8 @@ company= is enabled.
   + [[https://github.com/szermatt/emacs-bash-completion][bash-completion]]
 
 * Prerequisites
-This module has no prerequisites.
+[[https://fishshell.com/][=fish= shell]] for completions, falling back to [[https://www.gnu.org/software/bash/][=bash= shell]] if =fish= is not
+found. If neither shell is found, completions may not be available.
 
 * Features
 + Command completion with Company