Add elpaca to the README.md file

README.md

@@ -35,6 +35,7 @@ A [user commented on Reddit](https://www.reddit.com/r/emacs/comments/1feaf37/com
         - [Configuring LSP Servers with Eglot (built-in)](#configuring-lsp-servers-with-eglot-built-in)
         - [Code completion with corfu](#code-completion-with-corfu)
         - [How to configure straight.el?](#how-to-configure-straightel)
+        - [How to configure elpaca (package manager)](#how-to-configure-elpaca-package-manager)
         - [Which other customizations can be interesting to add?](#which-other-customizations-can-be-interesting-to-add)
     - [Frequently asked questions](#frequently-asked-questions)
         - [How to increase gc-cons-threshold?](#how-to-increase-gc-cons-threshold)
@@ -552,6 +553,50 @@ To configure `corfu` and `cape`, add the following to `~/.emacs.d/post-init.el`:
   (load bootstrap-file nil 'nomessage))
 ```
 
+### How to configure elpaca (package manager)
+
+[Add the elpaca bootstrap code](https://github.com/progfolio/elpaca?tab=readme-ov-file#installer) to `~/.emacs.d/pre-init.el`:
+``` elisp
+(defvar elpaca-installer-version 0.8)
+(defvar elpaca-directory (expand-file-name "elpaca/" user-emacs-directory))
+(defvar elpaca-builds-directory (expand-file-name "builds/" elpaca-directory))
+(defvar elpaca-repos-directory (expand-file-name "repos/" elpaca-directory))
+(defvar elpaca-order '(elpaca :repo "https://github.com/progfolio/elpaca.git"
+                              :ref nil :depth 1
+                              :files (:defaults "elpaca-test.el" (:exclude "extensions"))
+                              :build (:not elpaca--activate-package)))
+(let* ((repo  (expand-file-name "elpaca/" elpaca-repos-directory))
+       (build (expand-file-name "elpaca/" elpaca-builds-directory))
+       (order (cdr elpaca-order))
+       (default-directory repo))
+  (add-to-list 'load-path (if (file-exists-p build) build repo))
+  (unless (file-exists-p repo)
+    (make-directory repo t)
+    (when (< emacs-major-version 28) (require 'subr-x))
+    (condition-case-unless-debug err
+        (if-let* ((buffer (pop-to-buffer-same-window "*elpaca-bootstrap*"))
+                  ((zerop (apply #'call-process `("git" nil ,buffer t "clone"
+                                                  ,@(when-let* ((depth (plist-get order :depth)))
+                                                      (list (format "--depth=%d" depth) "--no-single-branch"))
+                                                  ,(plist-get order :repo) ,repo))))
+                  ((zerop (call-process "git" nil buffer t "checkout"
+                                        (or (plist-get order :ref) "--"))))
+                  (emacs (concat invocation-directory invocation-name))
+                  ((zerop (call-process emacs nil buffer nil "-Q" "-L" "." "--batch"
+                                        "--eval" "(byte-recompile-directory \".\" 0 'force)")))
+                  ((require 'elpaca))
+                  ((elpaca-generate-autoloads "elpaca" repo)))
+            (progn (message "%s" (buffer-string)) (kill-buffer buffer))
+          (error "%s" (with-current-buffer buffer (buffer-string))))
+      ((error) (warn "%s" err) (delete-directory repo 'recursive))))
+  (unless (require 'elpaca-autoloads nil t)
+    (require 'elpaca)
+    (elpaca-generate-autoloads "elpaca" repo)
+    (load "./elpaca-autoloads")))
+(add-hook 'after-init-hook #'elpaca-process-queues)
+(elpaca `(,@elpaca-order))
+```
+
 ### Which other customizations can be interesting to add?
 
 1. Read the following article from the same author: [Essential Emacs Packages for Efficient Software Development and Text Editing](https://www.jamescherti.com/essential-emacs-packages/)