Add 'Upgrading' documentation

[MarkEWaite]

• Page to migrate: Automated Upgrade
• Destination on jenkins.io: Installing section of User Handbook

Migration notes

Upgrade instructions depend on the initial installation method. Each section should recommend that long term support (LTS) users read the LTS upgrade guide for their release.

Upgrade Instructions need to include:

• Upgrading a standalone war file
• Upgrading a war file in a container (Tomcat, GlassFish, WebSphere, etc.)
• Upgrading a Docker image
• Upgrading a Debian/Ubuntu package
• Upgrading a CentOS/Red Hat package
• Upgrading a Fedora package
• Upgrading an OpenSUSE package
• Upgrading a Windows MSI package
• Upgrading a FreeBSD package
• Upgrading an OpenIndiana package

For contributors

• Wiki Migration Guidelines

[krharsh17]

I'd like to work on this issue. However, I think I will need a little help with requirements such as

• Upgrading a standalone war file
• Upgrading a Docker image

and others which have not been referenced to their docs. It would be helpful for me if someone could point me to where I can find these instructions.

[oleg-nenashev]

@MarkEWaite I would suggest to merge "Upgrading" into "Installing sections" .

@krharsh17

Upgrading a standalone war file

• https://www.thegeekstuff.com/2016/06/upgrade-jenkins-and-plugins/ looks reasonable, some steps could be taken from there

Upgrading a Docker image

You could just reference https://github.com/jenkinsci/docker#upgrading . No need to duplicate the information

[krharsh17]

@oleg-nenashev There's more

• Upgrading a CentOS/Red Hat package
• Upgrading an OpenSUSE package
• Upgrading a FreeBSD package
• Upgrading an OpenIndiana package

[MarkEWaite]

I like the suggestion from @oleg-nenashev that we include upgrade in the installation instructions instead of creating a separate page for upgrade.

Upgrading a CentOS / Red Hat package

yum update jenkins

Upgrading a Fedora package

dnf update jenkins

Upgrading an OpenSUSE package

zypper update jenkins

Upgrading a FreeBSD package

pkg update jenkins

Upgrading an OpenIndiana package

pkg update jenkins

[vsilverman]

I agree with @oleg-nenashev and @MarkEWaite . Also it may be useful adding TOC to The Docker Readme to facilitate UX experience of reading a large file. Here's a useful method. Should produce clickable references in any MarkDown editor.

---

Table of contents

1. Introduction
2. Some paragraph
   1. Sub paragraph
3. Another paragraph

This is the introduction

Some introduction text, formatted in heading 2 style

Some paragraph

The first paragraph text

Sub paragraph

This is a sub paragraph, formatted in heading 3 style

Another paragraph

The second paragraph text

---

Pls see if it make sense doing as part of this project or adding as a separate issue