Update linear_search.py (#2422)

* Update linear_search.py

Python implementation of recursive linear search algorithm

* Update linear_search.py

Added different doctests
Added the parameter hints
Handled the exception

* Update linear_search.py

added parameter hints to linear_search

* Update linear_search.py

Both the functions return the index if the target is found and -1 if it is not found
The rec_linear_search raises an exception if there is an indexing problem
Made changes in the doc comments

* Update linear_search.py

Co-authored-by: Christian Clauss <[email protected]>