Custom action alert notifications, new in 3.6.2

(cherry picked from commit 20e9a7dcdbca75065c619c63ec743f2d44c910b1)
Custom action spellfixes and minor adjustments after seeing published version

(cherry picked from commit 72e692750078f3e9e4f9645eaeb2999dc0a72501)
Add: Bash Exploit inventory and remediation tutorial
Change: Reorganize tutorial images

This tutorial has a bunch of images, it makes it hard to manage the
other content so I have moved all the images for this tutorial to a
specific sub directory.
Change: Fix broken image links shorten title
Rename images

Rename images so that they are easily identified and work.
Change: Add note about working with community
Merge pull request #923 from nickanderson/3.6-tutorial/bash_cve

Add: Tutorial for Reporting and Remediation of Security Vulnerabilities
Minor typo in methods.markdown
Change: Update pacakge URLs

Update to a more readable url for packages and use http instead of
https. There is no need to transfer these things over a secure
connection.
Merge pull request #926 from nickanderson/pick_docs

Change: Update pacakge URLs
Change: Fix link to old bucket

We don't need to preserve this outdated instruction just because a video
shows that URL. It is better to have up to date text, and not have the
quickinstall scripts duplicated in multiple places. Though we will
continue to publish the quickinstall script at the old location as well
for some time.
Merge pull request #924 from philregier/patch-1

Minor typo in methods.markdown
Merge pull request #928 from nickanderson/urlfix_

Change: Fix link to old bucket
Change: Update vagrant environment instruction URLs
Merge pull request #931 from nickanderson/update_vagrant_

Change: Update vagrant environment instruction URLs
Change: Fix typo in policy

Switching to paths provided by the stdlib I forgot to remove the
previously hard coded /bin/echo.
Merge pull request #936 from nickanderson/zendesk_1510_

Change: Fix typo in policy
example for custom action script to ease development

(cherry picked from commit 536017cff01f28635f9402065c672fb10e1d48b5)
Installation guide for HA.