[hackers] [libzahl] Fix typo || Mattias Andrée

[git]

commit b241d940ec7fc3574ab7510145bd3a4d8e6df5cb
Author:     Mattias Andrée <maand...@kth.se>
AuthorDate: Sun Mar 6 21:48:53 2016 +0100
Commit:     Mattias Andrée <maand...@kth.se>
CommitDate: Sun Mar 6 21:48:53 2016 +0100

    Fix typo
    
    Signed-off-by: Mattias Andrée <maand...@kth.se>

diff --git a/src/zmul.c b/src/zmul.c
index 5b35d93..9fba2e6 100644
--- a/src/zmul.c
+++ b/src/zmul.c
@@ -8,7 +8,7 @@ zmul(z_t a, z_t b, z_t c)
        /*
         * Karatsuba algorithm
         * 
-        * Basically, this how you were toughed to multiply large numbers
+        * Basically, this is how you were toughed to multiply large numbers
         * by hand in school: 4010⋅3020 = (4000 + 10)(3000 + 20) =
         = 40⋅30⋅10⁴ + (40⋅20 + 30⋅10)⋅10² + 10⋅20, but the 
middle is
         * optimised to only one multiplication: