[PATCH] few typo fixes to src/en/book/ch07.xml

[Kamesh Jayachandran]

Kamaraju Kusumanchi wrote:
> I think you are right Ben! I am from India and I have never heard anyone
> saying "an hint" or "an unique". I have never heard anyone say "an herb"
> either. As far as I know, all these words - {hint, unique, herb} go with 'a'.
>
> raju
>
>   

I also agree not remembering someone saying 'an hint', It is just that I 
overapplied :) the simple formula learnt in school. Anyway good learning 
for me.

With regards
Kamesh Jayachandran