add OctoRelay plugin (#821)

* add OctoRelay plugin

* fix screenshots example

* rename files (case sensitive) fix python version

Co-authored-by: Boris Burgstaller <boris.burgstaller@netcentric.biz>

Author: borisbu

_plugins/octorelay.md

@@ -0,0 +1,95 @@
+---
+layout: plugin
+
+id: octorelay
+title: OctoRelay
+description: A plugin to control relays or other things on the GPIO pins of your raspberry pi. For example turn the power of printer, the light or a fan ON and OFF via the web interface.
+
+authors:
+- Boris Burgstaller
+license: AGPLv3
+
+# today's date in format YYYY-MM-DD, e.g.
+date: 2021-03-13
+
+homepage: https://github.com/borisbu/OctoRelay
+source: https://github.com/borisbu/OctoRelay
+archive: https://github.com/borisbu/OctoRelay/archive/master.zip
+
+# Set this to true if your plugin uses the dependency_links setup parameter to include
+# library versions not yet published on pypi. SHOULD ONLY BE USED IF THERE IS NO OTHER OPTION!
+#follow_dependency_links: false
+
+tags:
+- raspberry pi
+- GPIO
+- relay
+- power
+- switch
+
+screenshots:
+- url: /assets/img/plugins/octorelay/screenshot.png
+  alt: navbar customization
+  caption: navbar customization
+- url: /assets/img/plugins/octorelay/settings.png
+  alt: settings
+  caption: settings
+
+featuredimage: /assets/img/plugins/octorelay/screenshot.png
+
+# You only need the following if your plugin requires specific OctoPrint versions or
+# specific operating systems to function - you can safely remove the whole
+# "compatibility" block if this is not the case.
+
+compatibility:
+
+  # List of compatible versions
+  #
+  # A single version number will be interpretated as a minimum version requirement,
+  # e.g. "1.3.1" will show the plugin as compatible to OctoPrint versions 1.3.1 and up.
+  # More sophisticated version requirements can be modelled too by using PEP440
+  # compatible version specifiers.
+  #
+  # You can also remove the whole "octoprint" block. Removing it will default to all
+  # OctoPrint versions being supported.
+
+  octoprint:
+  - 1.3.0
+
+  # List of compatible operating systems
+  #
+  # Possible values:
+  #
+  # - windows
+  # - linux
+  # - macos
+  # - freebsd
+  #
+  # There are also two OS groups defined that get expanded on usage:
+  #
+  # - posix: linux, macos and freebsd
+  # - nix: linux and freebsd
+  #
+  # You can also remove the whole "os" block. Removing it will default to all
+  # operating systems being supported.
+
+  os:
+  - linux
+
+  # Compatible Python version
+  #
+  # Plugins should aim for compatibility for Python 2 and 3 for now, in which case the value should be ">=2.7,<4".
+  #
+  # Plugins that only wish to support Python 3 should set it to ">=3,<4".
+  #
+  # If your plugin only supports Python 2 (worst case, not recommended for newly developed plugins since Python 2
+  # is EOL), leave at ">=2.7,<3"
+
+  python: ">=2.7,<4"
+
+---
+
+A plugin that adds buttons to the navigation bar to toggle GPIO pins on the Raspberry Pi.
+I use it with a 4 relay board, and printed this case for it: https://www.thingiverse.com/thing:2975944
+
+Just hooked up the GPIO pins with the relay board, and now I can turn the power of the printer, the fan and the light on and foo with OctoPrint.