doc: Add installation instructions for GitHub releases (#1099)

README.md

@@ -36,6 +36,7 @@ For the full documentation see https://box-project.github.io/box.
     1. [Phive](doc/installation.md#phive)
     1. [Composer](doc/installation.md#composer)
     1. [Homebrew](doc/installation.md#homebrew)
+    1. [GitHub](doc/installation.md#github)
 1. [Usage](#usage)
 1. [Configuration][the configuration documentation]
     1. [Base path (`base-path`)](doc/configuration.md#base-path-base-path)

doc/installation.md

@@ -4,6 +4,7 @@
 1. [Phive](#phive)
 1. [Composer](#composer)
 1. [Homebrew](#homebrew)
+1. [GitHub](#github)
 
 
 ## PHAR
@@ -66,6 +67,28 @@ To upgrade `box` use the following command:
 $ brew upgrade box
 ```
 
+## GitHub
+
+You may download the Box PHAR directly from the [GitHub release][github-release] directly.
+You should however beware that it is not as secure as downloading it from the other mediums.
+Hence, it is recommended to check the signature when doing so:
+
+```
+# Do adjust the URL based on the latest release
+wget -O box.phar "https://github.com/box-project/box/releases/download/4.4.0/box.phar"
+wget -O box.phar.asc "https://github.com/box-project/box/releases/download/4.4.0/box.phar.asc"
+
+# Check that the signature matches
+gpg --verify box.phar.asc box.phar
+
+# Check the issuer (the ID can also be found from the previous command)
+gpg --keyserver hkps://keys.openpgp.org --recv-keys 41539BBD4020945DB378F98B2DF45277AEF09A2F
+
+rm box.phar.asc
+chmod +x box.phar
+```
+
+
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 <hr />