first attempt at a new student lesson
fixed some formatting and grammer errors
proposed replacement for shell-overview
Fixed the copious spelling errors
fixed 'grant_proposal' directory errors
revert tab completion to 'twice'
reinstate metadata
shell-filedir notebook directory reorganization

* removed redundant instructor notebook
* renamed shell-overview more appropriately to shell-filedir
Suggested revisions to PR #93

Very minor editing and fixes
@wltrimbl's suggested fixes
Merge pull request #153 from swcarpentry/pr-93-suggested-edits

PR 93 suggested edits