crontab basics

How to list, create, edit and delete cron jobs.  Also describes crontab fields.
Added output of crontab command to file
Changed markdown syntax
cat basics

Includes: to standard output, to another file, and combining files
Fixed typo.  I think it was supposed to be "extracting data", not "estracting data"
Moves datacenter topics to a subdirectory
Clarified the purpose of each layer of the OSI model.
Merge pull request #33 from miketheman/dc_subdirs

Moves datacenter topics to a subdirectory
Monospaced commands and file paths per @avleen's suggestion
Removed double spaces between sentences and limited lines to 80 characters.
Bit of a hodge-podge commit.  Made changes per all but one of the remaining suggestions.
Pedantic typo correction
Merge pull request #40 from mattt416/fix_typo_in_package_management_101

Pedantic typo correction
Add a pro tip section & a (hopefully) helpful tip
Merge pull request #41 from mattt416/database_101_pro_tip

Add a pro tip section & a (hopefully) helpful tip
initial text for signals
Made some grammatical fixes and added terms to glossary.
updated soft skills section
updated soft skills section
updated soft skills section