Move parts of the documentation from GitHub wiki to CPAN modules

[nichtich]

The current GitHub wiki contains 32 pages, which are compiled based on the table of contents at wiki page "Home" to http://librecat.org/Catmandu. As discussed at the Workshop in Berlin, most of the documentation should be moved to CPAN modules:

• Catmandu::Introduction
• https://github.com/LibreCat/Catmandu/wiki/Installation=> Catmandu::Help::Installation
• https://github.com/LibreCat/Catmandu/wiki/Contribution => Catmandu::Help::Contributing
• https://github.com/LibreCat/Catmandu/wiki/Development-Setup => Catmandu::Help::Development_Setup
• https://github.com/LibreCat/Catmandu/wiki/Patch-Submission => Catmandu::Help::Patch_Submission
• https://github.com/LibreCat/Catmandu/wiki/Concepts=> Catmandu::Help::Glossary
• https://github.com/LibreCat/Catmandu/wiki/Fixes-Cheat-Sheet=> Catmandu::Help::Cheatsheet (section "Fixes")
• https://github.com/LibreCat/Catmandu/wiki/Command-line-client-Cheat-Sheet=> Catmandu::Help::Cheatsheet (section "Command line")

etc.

Content of these modules can then be

[jorol]

created Catmandu::Help::Installation, see pr #289

[jorol]

added Catmandu::Help::Contribtution, Catmandu::Help::Development_Setup and Catmandu::Help::Patch_Submission in pr #290

[nichtich]

The help modules are in an unreleased and unmerged branch - what's the plan to make them public?

[phochste]

Is there a good plan how to maintain these man pages? I see still people contributing to the Wiki page. What is needed is that we need to decide to keep or kill the Wiki, have a way to publish these man pages as HTML pages on our website.