docs: mention 29.1 support

Now that 29.1 is stable, support for it is official. This updates or
docs and doctor checks to take this into account. I've also included a
link to a Discourse post where I track support for Emacs HEAD.

README.md

@@ -5,7 +5,7 @@
 [Install](#install) • [Documentation] • [FAQ] • [Screenshots] • [Contribute](#contribute)
 
 ![Made with Doom Emacs](https://img.shields.io/github/tag/doomemacs/doomemacs.svg?style=flat-square&label=release&color=58839b)
-![Supports Emacs 27.1 - 28.1](https://img.shields.io/badge/Supports-Emacs_27.1--28.1-blueviolet.svg?style=flat-square&logo=GNU%20Emacs&logoColor=white)
+![Supports Emacs 27.1–29.1](https://img.shields.io/badge/Supports-Emacs_27.1–29.1-blueviolet.svg?style=flat-square&logo=GNU%20Emacs&logoColor=white)
 ![Latest commit](https://img.shields.io/github/last-commit/doomemacs/doomemacs/master?style=flat-square)
 ![Build status: master](https://img.shields.io/github/workflow/status/doomemacs/doomemacs/CI/master?style=flat-square)
 [![Discord Server](https://img.shields.io/discord/406534637242810369?color=738adb&label=Discord&logo=discord&logoColor=white&style=flat-square)][Discord]
@@ -99,7 +99,12 @@ Check out [the FAQ][FAQ] for answers to common questions about the project.
 
 # Prerequisites
 + Git 2.23+
-+ Emacs 27.1+ (*28.1 is recommended*, or [native-comp](https://www.emacswiki.org/emacs/GccEmacs). **29+ is not supported**).
++ Emacs 27.1–29.1 (**Recommended: 29.1 +
+  [native-comp](https://www.emacswiki.org/emacs/GccEmacs)**)
+  > :warning: Unstable and pre-release builds of Emacs -- which end in `.50`,
+  > `.60`, or `.9X` (e.g. `28.1.91`) -- **are not officially supported**. There
+  > *is* some effort to support Emacs HEAD, however. [Follow this Discourse
+  > post](https://discourse.doomemacs.org/t/3241) for details.
 + [ripgrep] 11.0+
 + GNU `find`
 + *OPTIONAL:* [fd] 7.3.0+ (improves file indexing performance for some commands)

lisp/cli/doctor.el

@@ -54,27 +54,27 @@ in."
 
   (print! (start "Checking your Emacs version..."))
   (print-group!
-    (cond ((or (> emacs-major-version 28)
-               (string-match-p ".\\(50\\|9[0-9]\\)$" emacs-version))
+    (cond ((or (> emacs-major-version 29)
+               (string-match-p ".\\([56]0\\|9[0-9]\\)$" emacs-version))
            (warn! "Detected a development version of Emacs (%s)" emacs-version)
-           (if (> emacs-major-version 28)
-               (explain! "This is the bleeding edge of Emacs. Doom does not support it because Emacs "
-                         "HEAD is in an especially unstable period of its development. If you've found "
-                         "a stable commit, great! But be cautious about updating too eagerly!\n")
-             (explain! "A .50 or .9x appended to the version string indicates that this is a version of "
-                       "Emacs in between stable releases. These are not well supported.\n"))
+           (if (> emacs-major-version 29)
+               (explain! "This is the bleeding edge of Emacs. As it is constantly changed, Doom will not "
+                         "(officially) support it. If you've found a stable commit, great! But be "
+                         "cautious about updating Emacs too eagerly!\n")
+             (explain! "A .50, .60, or .9X appended to the version string indicates that this is a version "
+                       "of Emacs in between stable releases. These are not well supported.\n"))
            (explain! "Because development builds are prone to random breakage, there will be a greater "
                      "burden on you to investigate and deal with issues. Please make extra sure that "
-                     "your issue is reproducible in 28.1 before reporting them to Doom's issue tracker!\n"
+                     "your issue is reproducible in 29.1 before reporting them to Doom's issue tracker!\n"
                      "\n"
                      "If this doesn't phase you, read the \"Why does Doom not support Emacs HEAD\" QnA "
                      "in Doom's FAQ. It offers some advice for debugging and surviving issues on the "
-                     "bleeding edge. Failing that, 28.1 is highly recommended and will always be "
+                     "bleeding edge. Failing that, 29.1 is highly recommended and will always be "
                      "Doom's best supported version of Emacs."))
           ((= emacs-major-version 27)
            (warn! "Emacs 27 is supported, but consider upgrading to 28.1")
            (explain! "Emacs 28.1 is better supported, faster, and more stable. Plus, Doom will drop "
-                     "27.x support sometime mid-2022."))))
+                     "27.x support sometime late-2023."))))
 
   (print! (start "Checking for Doom's prerequisites..."))
   (print-group!