Doc link in plugin settings page point to non existing GitBook

[hanzei]

The links from the settings page (

mattermost-plugin-jira/plugin.json

Lines 23 to 24 in 8a1f5b5

"header": "Please refer to the '/jira' command [**documentation**](https://mattermost.gitbook.io/plugin-jira/setup/installation#step-2-install-app-on-jira-server) to further configure the Jira plugin.",

"footer": "Please refer to the '/jira' command [**documentation**](https://mattermost.gitbook.io/plugin-jira/setup/installation#step-2-install-app-on-jira-server) to further configure the Jira plugin. Specifically, ['/jira instance [un-]install'](https://mattermost.gitbook.io/plugin-jira/setup/installation#step-2-install-app-on-jira-server) and ['/jira webhook'](https://mattermost.gitbook.io/plugin-jira/setup/configuration#step-4-required-setup-webhooks-from-jira).",

) point to GitBook, which is not longer used. They should point to the README instead.

[hanzei]

@mattermost/contractor-brightscout Can you please take a look? cc @mickmister

[mickmister]

I believe these should be pointing to permalinks now. @cwarnermm Is this correct?

[cwarnermm]

@mickmister - Permalinks are used in-product for docs/web links. Plugins and integrations can use direct links to README content in repositories.