remove mention of for loop

Couldn't see a mention of for loops, perhaps it was in an earlier version, or yet to appear?
Update 01-starting-with-data.Rmd
Update 01-starting-with-data.Rmd
finally adding shell lessons and cheatsheets for shell and sql
added excel lesson directory
Added CONTRIBUTING.md file for information on how to contribute to the repo
moved files from data into data/biology so there can be other datasets
added directory for python materials
Create ecology_spreadsheets
Merge pull request #6 from cbahlai/master

Create ecology_spreadsheets
added md extension to Markdown file
Merge pull request #3 from benmarwick/master

remove mention of for loop
Add images for lesson
Update ecology_spreadsheets.md
Added info about man command and file naming with whitespaces
Merge pull request #7 from cbahlai/patch-2

Update ecology_spreadsheets.md
Started working on examples with bio data
Added sublime to text editors
Merging Christie's file ecology_spreadsheets.md
Splitted lessons into files and put them into eco-examples directory