session 2: line 147 - add prompt for what to search for in help

[jayware9]

We might need to explicitly prompt with "bind" to find the function, especially for those doing self study.

decision: get feedback from self study on what needs to change

https://github.com/DataScienceScotland/intro_to_r/blob/17b78f13c38c16da9f22902a802a29f426d58f68/session2/intro_to_R_session2_incomplete.Rmd#L147