doc/packages/emacs.section.md: reword

doc/packages/emacs.section.md

@@ -1,8 +1,16 @@
 # Emacs {#sec-emacs}
 
+[Emacs](https://www.gnu.org/software/emacs/) is the advanced, extensible, customizable, self-documenting editor.
+
+At its core is an interpreter for Emacs Lisp (shortly, Elisp), a dialect of the Lisp programming language with extensions to support text editing.
+
 ## Configuring Emacs {#sec-emacs-config}
 
-The Emacs package comes with some extra helpers to make it easier to configure. `emacs.pkgs.withPackages` allows you to manage packages from ELPA. This means that you will not have to install that packages from within Emacs. For instance, if you wanted to use `company` `counsel`, `flycheck`, `ivy`, `magit`, `projectile`, and `use-package` you could use this as a `~/.config/nixpkgs/config.nix` override:
+Nixpkgs provides a framework that leverages Emacs via Nix.
+
+`emacs.pkgs.withPackages` allows managing packages from various Elisp package repositories (ELPA, MELPA etc.) and even third-party stand-alone packages from Nix, without relying on Emacs to download and install them.
+
+For instance, by writing the code below at `~/.config/nixpkgs/config.nix`, the Elisp packages `company` `counsel`, `flycheck`, `ivy`,`magit`, `projectile`, and `use-package` are installed:
 
 ```nix
 {
@@ -20,7 +28,16 @@ The Emacs package comes with some extra helpers to make it easier to configure.
 }
 ```
 
-You can install it like any other packages via `nix-env -iA myEmacs`. However, this will only install those packages. It will not `configure` them for us. To do this, we need to provide a configuration file. Luckily, it is possible to do this from within Nix! By modifying the above example, we can make Emacs load a custom config file. The key is to create a package that provides a `default.el` file in `/share/emacs/site-start/`. Emacs knows to load this file automatically when it starts.
+This package can be installed like any other, via `nix-env -iA myEmacs`.
+
+However, this expression merely installs the package. It will not _configure_ them.
+To do this, we need to provide a configuration file.
+
+Luckily, it is possible to do this from within Nix!
+
+By modifying the above example, we can make Emacs load a custom config file.
+The key is to create a package that provides a `default.el` file in `/share/emacs/site-start/`.
+Emacs loads this file automatically when it starts.
 
 ```nix
 {
@@ -97,9 +114,14 @@ You can install it like any other packages via `nix-env -iA myEmacs`. However, t
 }
 ```
 
-This provides a fairly full Emacs start file. It will load in addition to the user's personal config. You can always disable it by passing `-q` to the Emacs command.
+This provides a fairly full Emacs start file. It will be loaded in addition to the user's personal config. It is always possible to disable it, by passing `-q` as a command line argument to Emacs.
+
+Sometimes `emacs.pkgs.withPackages` is not enough, as this package set imposes some priorities over their packages (with the lowest priority assigned to GNU-devel ELPA, and the highest for packages manually defined in `pkgs/applications/editors/emacs/elisp-packages/manual-packages`).
+
+But it is not possible to control these priorities when some package is installed as a dependency. The overrides can be done on a per-package-basis, providing all the required dependencies manually. However this procedure is tedious and there is always a possibility that an unwanted dependency sneaks in through some other package. 
+
+A complete and pervasive override for such a package can be done via `overrideScope`.
 
-Sometimes `emacs.pkgs.withPackages` is not enough, as this package set has some priorities imposed on packages (with the lowest priority assigned to GNU-devel ELPA, and the highest for packages manually defined in `pkgs/applications/editors/emacs/elisp-packages/manual-packages`). But you can't control these priorities when some package is installed as a dependency. You can override it on a per-package-basis, providing all the required dependencies manually, but it's tedious and there is always a possibility that an unwanted dependency will sneak in through some other package. To completely override such a package, you can use `overrideScope`.
 
 ```nix
 let