lab 6: hashes updates

[aaronbloomfield]

• better explain getWordInTable(), including when and why it will return a string shorter than the length parameter passed in; this can be in the lab doc or in comments in the source code (or both)
  • consider renaming it to getWordInGrid() to remove confusion between that and the hash table
• better explain the use of big-Theta in this lab: that it applies to just the word search part, and not the entire program