Updates to the README document

Author: MarkBaker

README.md

@@ -3,7 +3,7 @@ PHPComplex
 
 ---
 
-PHP Class for handling Complex numbers
+PHP Class Library for working with Complex numbers
 
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@@ -65,6 +65,24 @@ together with functions for
 
 ---
 
+# Installation
+
+```shell
+composer require markbaker/complex:^3.0
+```
+
+# Important BC Note
+
+If you've previously been using procedural calls to functions and operations using this library, then from version 3.0 you should use [MarkBaker/PHPComplexFunctions](https://github.com/MarkBaker/PHPComplexFunctions) instead (available on packagist as [markbaker/complex-functions](https://packagist.org/packages/markbaker/complex-functions)).
+
+You'll need to replace `markbaker/complex`in your `composer.json` file with the new library, but otherwise there should be no difference in the namespacing, or in the way that you have called the Complex functions in the past, so no actual code changes are required.
+
+```shell
+composer require markbaker/complex-functions:^1.0
+```
+
+You should not reference this library (`markbaker/complex`) in your `composer.json`, composer wil take care of that for you.
+
 # Usage
 
 To create a new complex object, you can provide either the real, imaginary and suffix parts as individual values, or as an array of values passed passed to the constructor; or a string representing the value. e.g
@@ -117,7 +135,7 @@ echo Complex\Operations::add($complexString1, $complexString2);
 ```
 If you want to perform the same operation against multiple values (e.g. to add three or more complex numbers), then you can pass multiple arguments to any of the operations.
 
-You can pass these arguments as Complex objects, or as an array or string that will parse to a complex object.
+You can pass these arguments as Complex objects, or as an array, or string that will parse to a complex object.
 
 ## Using functions
 
@@ -135,6 +153,8 @@ $complexString = '1.23-4.56i';
 
 echo Complex\Functions::sinh($complexString);
 ```
+As with operations, you can pass these arguments as Complex objects, or as an array or string that will parse to a complex object.
+
 
 In the case of the `pow()` function (the only implemented function that requires an additional argument) you need to pass both arguments when calling the function