Rename master branch to 0.9.x and update installation instructions

Author: clue

README.md

@@ -4,22 +4,24 @@
 
 Common mathematical graph algorithms implemented in PHP
 
->   You're viewing the contents of the `master` development brach. Note that this
-    branch is subject to active development and will contain breaking changes
-    for the upcoming release. If you want to use the latest release version,
-    see also the `v0.8.x` release branch for more details.
-
->   Note: This project is in beta stage! Feel free to report any issues you encounter.
+> **Development version:** This branch contains the code for the upcoming
+> version 0.9. For the code of the current stable version 0.8, check out the
+> [`0.8.x` branch](https://github.com/graphp/algorithms/tree/0.8.x).
+>
+> The upcoming version 0.9 will be the way forward for this package. However,
+> we will still actively support version 0.8 for those not yet on the latest
+> version. See also [installation instructions](#install) for more details.
 
 ## Install
 
-The recommended way to install this library is [through Composer](https://getcomposer.org).
+The recommended way to install this library is [through Composer](https://getcomposer.org/).
 [New to Composer?](https://getcomposer.org/doc/00-intro.md)
 
-This will install the latest supported version:
+Once released, this project will follow [SemVer](https://semver.org/).
+At the moment, this will install the latest development version:
 
 ```bash
-$ composer require graphp/algorithms:^0.8.2
+composer require graphp/algorithms:^0.9@dev
 ```
 
 See also the [CHANGELOG](CHANGELOG.md) for details about version upgrades.
@@ -32,18 +34,18 @@ It's *highly recommended to use PHP 7+* for this project.
 ## Tests
 
 To run the test suite, you first need to clone this repo and then install all
-dependencies [through Composer](https://getcomposer.org):
+dependencies [through Composer](https://getcomposer.org/):
 
 ```bash
-$ composer install
+composer install
 ```
 
 To run the test suite, go to the project root and run:
 
 ```bash
-$ php vendor/bin/phpunit
+vendor/bin/phpunit
 ```
 
 ## License
 
-Released under the terms of the permissive [MIT license](http://opensource.org/licenses/MIT).
+This project is released under the permissive [MIT license](LICENSE).

composer.json

@@ -12,7 +12,7 @@
     ],
     "require": {
         "php": ">=5.3",
-        "graphp/graph": "dev-master#fb198e4 as 1.0.0"
+        "graphp/graph": "1.x-dev#fb198e4 as 1.0.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^9.3 || ^5.7 || ^4.8.35"