Update README.md

README.md

@@ -53,20 +53,20 @@ if($f1->parse_error=='') echo($f1->compute());
 else echo($f1->parse_error."<br>\n"); // Too many closing parenthesis !
 ```
 
-**Use of a indexed array**
+**Using an indexed array**
 ```PHP
 $f1 = new Formula1('toto*primes[6]',['toto'=>10,'primes'=>[2,3,5,7,11,13,17,19,23,29,31]]);
 echo($f1->compute()."<br>\n"); //170
 ```
 
-**Use of a key-value array**
+**Using a key-value array**
 ```PHP
 $f1 = new Formula1('toto*myar["zorglub_99"]',['toto'=>10,'myar'=>['aaa'=>2.5,'zorglub_99'=>5.5]]);
 echo($f1->compute()."<br>\n"); //55
 ```
 
 
-**Use offunctions**
+**Using math functions**
 ```PHP
 $f1 = new Formula1('2*5+sin(pi()/4)');
 echo($f1->compute()."<br>\n"); //7.071...