Add nightly build instllation instructions

Author: per1234

Diff for: README.md

@@ -9,10 +9,24 @@
 - Sketches
 - Libraries
 
+## Documentation
+
 For usage instructions, see [the documentation](https://arduino.github.io/arduino-lint/latest/)
 
 ## Continuous Integration
 
 There is a GitHub Actions action that makes it easy to use **arduino-lint**` in your CI workflows!
 
 See https://github.com/arduino/arduino-lint-action for more information.
+
+## How to contribute
+
+Contributions are welcome!
+
+Please see the [How to contribute](https://arduino.github.io/arduino-lint/latest/CONTRIBUTING/) page for information on
+building the source code, running tests, and contributing your changes to the project.
+
+### Beta testing
+
+[Nightly builds](https://arduino.github.io/arduino-lint/latest/installation/#nightly-builds) are available for beta
+testing.

Diff for: docs/CONTRIBUTING.md

@@ -8,11 +8,13 @@ There are several ways you can get involved:
 | ------------------------------------------------- | ------------------------------------------------------- |
 | - Support request<br/>- Question<br/>- Discussion | Post on the [Arduino Forum][forum]                      |
 | - Bug report<br/>- Feature request                | Issue report (read the [issue guidelines][issues])      |
+| Beta testing                                      | Try out the [nightly build][nightly]                    |
 | - Bug fix<br/>- Enhancement                       | Pull Request (read the [pull request guidelines][prs])  |
 | Monetary                                          | - [Donate][donate]<br/>- [Buy official products][store] |
 
 [forum]: https://forum.arduino.cc/index.php?board=3.0
 [issues]: #issue-reports
+[nightly]: installation.md#nightly-builds
 [prs]: #pull-requests
 [donate]: https://www.arduino.cc/en/Main/Contribute
 [store]: https://store.arduino.cc
@@ -26,6 +28,7 @@ High quality bug reports and feature requests are valuable contributions to the
 
 ### Before reporting an issue
 
+- Give the [nightly build](installation.md#nightly-builds) a test drive to see if your issue was already resolved.
 - Search [existing pull requests and issues](https://github.com/arduino/arduino-lint/issues?q=) to see if it was already
   reported. If you have additional information to provide about an existing issue, please comment there. You can use
   [GitHub's "Reactions" feature](https://github.com/blog/2119-add-reactions-to-pull-requests-issues-and-comments) if you

Diff for: docs/installation.md

@@ -53,6 +53,30 @@ already in your `PATH` or add the arduino-lint installation path to your `PATH`
 
 These are available from the "Assets" sections on the [releases page](https://github.com/arduino/arduino-lint/releases).
 
+#### Nightly builds
+
+These builds are generated every day at 01:00 GMT from the `main` branch and should be considered unstable. In order to
+get the latest nightly build available for the supported platform, use the following links:
+
+| Platform  |                              |                              |
+| --------- | ---------------------------- | ---------------------------- |
+| Linux     | [32 bit][linux32-nightly]    | [64 bit][linux64-nightly]    |
+| Linux ARM | [32 bit][linuxarm32-nightly] | [64 bit][linuxarm64-nightly] |
+| Windows   | [32 bit][windows32-nightly]  | [64 bit][windows64-nightly]  |
+| macOS     |                              | [64 bit][macos-nightly]      |
+
+[linux64-nightly]: https://downloads.arduino.cc/arduino-lint/nightly/arduino-lint_nightly-latest_Linux_64bit.tar.gz
+[linux32-nightly]: https://downloads.arduino.cc/arduino-lint/nightly/arduino-lint_nightly-latest_Linux_32bit.tar.gz
+[linuxarm64-nightly]: https://downloads.arduino.cc/arduino-lint/nightly/arduino-lint_nightly-latest_Linux_ARM64.tar.gz
+[linuxarm32-nightly]: https://downloads.arduino.cc/arduino-lint/nightly/arduino-lint_nightly-latest_Linux_ARMv7.tar.gz
+[windows64-nightly]: https://downloads.arduino.cc/arduino-lint/nightly/arduino-lint_nightly-latest_Windows_64bit.zip
+[windows32-nightly]: https://downloads.arduino.cc/arduino-lint/nightly/arduino-lint_nightly-latest_Windows_32bit.zip
+[macos-nightly]: https://downloads.arduino.cc/arduino-lint/nightly/arduino-lint_nightly-latest_macOS_64bit.tar.gz
+
+> These links return a `302: Found` response, redirecting to latest generated builds by replacing `latest` with the
+> latest available build date, using the format YYYYMMDD (i.e for 2019-08-06 `latest` is replaced with `20190806` )
+
+Checksums for the nightly builds are available at
 `https://downloads.arduino.cc/arduino-lint/nightly/nightly-<DATE>-checksums.txt`
 
 ### Build from source