doc: remove outdated AUCTEX reference

See #454

Author: progfolio

doc/elpaca.texi

@@ -640,7 +640,7 @@ It must return a version string understood by @samp{version-to-list}.
 e.g.
 
 @lisp
-(elpaca (auctex :version (lambda (_) (require 'tex-site) AUCTeX-version)))
+(elpaca (example :version (lambda (_) "1.0.0")))
 @end lisp
 
 @node vars

doc/manual.md

@@ -508,7 +508,7 @@ The name of the file the package’s autoload file. When `nil`, autoload loa
 A function which must accept an Elpaca struct as its sole argument. It must return a version string understood by `version-to-list`. e.g.
 
 ```emacs-lisp
-(elpaca (auctex :version (lambda (_) (require 'tex-site) AUCTeX-version)))
+(elpaca (example :version (lambda (_) "1.0.0")))
 ```
 
 

doc/manual.org

@@ -368,7 +368,7 @@ It must return a version string understood by =version-to-list=.
 e.g.
 
 #+begin_src emacs-lisp :lexical t :eval never
-(elpaca (auctex :version (lambda (_) (require 'tex-site) AUCTeX-version)))
+(elpaca (example :version (lambda (_) "1.0.0")))
 #+end_src
 
 **** :vars