[O] Documentation: Babel scheme support and geiser

[Jarmo Hurri]

Greetings.

I started doing some Schemeing in org, and bumped into a couple of
documentation issues I wanted to check / report.

In short, I wonder whether
1. geiser should be listed as a scheme requirement in worg
2. ob-scheme.el should point to MELPA instead of ELPA for geiser.

The long version
----------------

First, worg lists no requirements for use of scheme

https://orgmode.org/worg/org-contrib/babel/languages.html

but typing C-c C-c in a scheme block gives error

org-babel-execute-src-block: Symbol’s value as variable is void:
geiser-default-implementation

Second, file ob-scheme.el tells me that

;; - for session based evaluation geiser is required, which is available from
;;   ELPA.

However, neither the ELPA page

https://elpa.gnu.org/packages/

nor "M-x list-packages" list geiser as an available package.

It does seem, however, that geiser _is_ available from MELPA

http://stable.melpa.org/#/geiser

(or git directly).

All the best,

Jarmo