Added BASH books

[amitech]

Added links of BASH and unix programming books

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[lynxlynxlynx]

Looks ok, but adding readable link text would improve it. Check the previous entries.

[amitech]

@lynxlynxlynx thanks, I made suggested changes.

[lynxlynxlynx]

But why Amazon Smile, when you had them on Amazon (and one link still points there)? Just be consistent.

[amitech]

Corrected it now. Thanks.

[lynxlynxlynx]

LGTM