app/write: major refactor+rewrite

+ Make synosaurus unconditional
+ Move much of +write-mode into its hook
+ Conform README.org to template and expand it
+ Try to guess langtool-language-tool-jar
+ Update init.example.el entry
+ Remove redundant variables
+ Add +write-text-scale & +text-line-spacing variables

modules/app/write/packages.el

@@ -1,11 +1,11 @@
 ;; -*- no-byte-compile: t; -*-
 ;;; app/write/packages.el
 
+(package! synosaurus)
+(package! mixed-pitch)
+
 (when (featurep! +langtool)
   (package! langtool))
 (when (featurep! +wordnut)
   (package! wordnut))
-(when (featurep! +synosaurus)
-  (package! synosaurus))
 
-(package! mixed-pitch)