BCMath require by telescope fix syntax/grammer

OK 
Now I understanding the rules of Laravel Document :
I must to write it more accurate, so I  fix the grammar/syntax : 
we have to write: BCMath (respectively to : XML, JSON ,POO, OpenSSL)
and not  Bcmath 

sources(php.net):
https://secure.php.net/manual/en/book.bc.php
https://secure.php.net/manual/en/intro.bc.php
https://secure.php.net/manual/en/ref.bc.php

installation.md

@@ -28,7 +28,7 @@ However, if you are not using Homestead, you will need to make sure your server
 - XML PHP Extension
 - Ctype PHP Extension
 - JSON PHP Extension
-- Bcmath PHP Extension
+- BCMath PHP Extension
 </div>
 
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