doc/adding editorconfig and hl-column-fill documentation (#3815)

* doc/adding editor config and hl-column-fill docs

* Adding inaugural versons to the modules

* Making the requested edits

* adding in some more spaces

* redoing the review

* ui/fill-column: correct & expand readme

Co-authored-by: Henrik Lissner <henrik@lissner.net>

modules/ui/fill-column/README.org

@@ -0,0 +1,92 @@
+#+TITLE:   ui/fill-column
+#+DATE:    August 23, 2020
+#+SINCE:   2.0.9
+#+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]]
+  - [[#setting-fill-column-globally][Setting fill-column globally]]
+  - [[#setting-fill-column-for-the-current-buffer-or-mode][Setting fill-column for the current buffer or mode]]
+  - [[#hl-fill-column-only-configuring-the-look-of-the-indicator][(hl-fill-column only) Configuring the look of the indicator]]
+- [[#troubleshooting][Troubleshooting]]
+
+* Description
+This module provides a fill column indicator to make it obvious when a line
+reaches or surpasses the 80th column. This serves as a reminder to keep lines
+short for accessibility and/or convenience. [[https://www.emacswiki.org/emacs/EightyColumnRule][Read more about this on the Emacs
+Wiki page]].
+
+#+begin_quote
+This module is deprecated and will be removed once Doom drops Emacs 26.x
+support. This is because the built-in ~display-fill-column-indicator-mode~ (in
+27 and newer) replaces it, and enabling it is a trivial one-liner, which doesn't
+warrant a module: ~(global-display-fill-column-indicator-mode +1)~
+#+end_quote
+
+** Maintainers
+This module has no dedicated maintainers.
+
+** Module Flags
+This module provides no flags.
+
+** Plugins
++ [[https://github.com/laishulu/hl-fill-column][hl-fill-column]]* (unless Emacs >=27)
+
+* Prerequisites
+This module has no prerequisites.
+
+* Features
+The behavior of this module varies slightly depending on your version of Emacs:
+
++ In Emacs 26.x, text beyond ~fill-column~ will be highlighted.
++ In Emacs 27 and newer, a line is drawn down the right side at column 80.
+
+* Configuration
+** Setting fill-column globally
+This column limit is controlled by the ~fill-column~ variable (default: ~80~).
+
+This variable is buffer-local, therefore, to change this globally, you must use
+~setq-default~:
+
+#+BEGIN_SRC emacs-lisp
+(setq-default fill-column 100)
+#+END_SRC
+
+~hl-fill-column-mode~ (or ~display-fill-column-indicator-mode~ on Emacs 27+)
+must be restarted to see the change.
+
+** Setting fill-column for the current buffer or mode
+The ~setq-hook!~ convenience macro makes settings ~fill-column~ for a particular
+mode (or modes) easy:
+
+#+BEGIN_SRC emacs-lisp
+(setq-hook! 'org-mode-hook fill-column 100)
+(setq-hook! 'python-mode-hook fill-column 72)
+(setq-hook! js2-mode fill-column 72)
+(setq-hook! '(ruby-mode rustic-mode python-mode-hook) fill-column 80)
+#+END_SRC
+
+Any open buffers in these modes must be restarted to see the change.
+
+** (hl-fill-column only) Configuring the look of the indicator
+To change the appears of hl-fill-column's highlight, change the
+~hl-fill-column-face~ face. Doom provides the ~custom-set-faces!~ macro to help
+you do this:
+
+#+BEGIN_SRC emacs-lisp
+(custom-set-faces!
+  '(hl-fill-column-face :background "red"
+                        :foreground "blue"
+                        :inverse-video t))
+#+END_SRC
+
+See =M-x helpful-function RET custom-set-faces\!= for demos and documentation
+for this macro.
+
+* TODO Troubleshooting