Add :lang yaml module

Removes yaml-mode from :lang data and adds LSP support (#2502).

Closes #2502

Co-authored-by: Seong Yong-ju <sei40kr@gmail.com>

modules/lang/data/config.el

@@ -37,9 +37,6 @@
 (after! jsonnet-mode
   (set-electric! 'jsonnet-mode :chars '(?\n ?: ?{ ?})))
 
-(after! yaml-mode
-  (setq-hook! 'yaml-mode-hook tab-width yaml-indent-offset))
-
 
 ;;
 ;;; Frameworks

modules/lang/data/packages.el

@@ -3,7 +3,6 @@
 
 (package! graphql-mode :pin "7c37aee28b")
 (package! jsonnet-mode :pin "d8b486c837")
-(package! yaml-mode :pin "cecf4b106b")
 (package! csv-mode :pin "635337407c")
 (package! dhall-mode :pin "ef4d33debe")
 (package! protobuf-mode

modules/lang/yaml/README.org

@@ -0,0 +1,38 @@
+#+TITLE:   lang/yaml
+#+DATE:    April 23, 2020
+#+SINCE:   v3.0.0
+#+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 support for the [[https://yaml.org/][YAML file format]].
+
+** Maintainers
+This module has no dedicated maintainers.
+
+** Module Flags
++ =+lsp= Enables integration with LSP servers. Requires the =:tools lsp= module to be enabled.
+
+** Plugins
++ [[https://github.com/yoshiki/yaml-mode][yaml-mode]]
+
+* Prerequisites
+This module has no prereqisites.
+
+* TODO Features
+# An in-depth list of features, how to use them, and their dependencies.
+
+* TODO Configuration
+# How to configure this module, including common problems and how to address them.
+
+* TODO Troubleshooting
+# Common issues and their solution, or places to look for help.

modules/lang/yaml/config.el

@@ -0,0 +1,9 @@
+;;; lang/yaml/config.el -*- lexical-binding: t; -*-
+
+(use-package! yaml-mode
+  :hook "Procfile\\'"
+  :init
+  (when (featurep! +lsp)
+    (add-hook 'yaml-mode-local-vars-hook #'lsp!))
+  :config
+  (setq-hook! 'yaml-mode-hook tab-width yaml-indent-offset))

modules/lang/yaml/packages.el

@@ -0,0 +1,4 @@
+;; -*- no-byte-compile: t; -*-
+;;; lang/yaml/packages.el
+
+(package! yaml-mode :pin "cecf4b106b")