el-get-recipes.el: Docstring fixes.

This fixes a few `checkdoc' errors and some column length issues.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
Add special-mode for el-get-check-recipes.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
Info manual: Document `test-recipe.sh'.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
Merge pull request #1526 from ruediger/el-get-check-mode

El-get check mode and minor doc fixes.