Adding Linear Search

[JasonJTomlin]

Linear Search added. Another search for the collection!

[abranhe]

Hi, @JasonJTomlin thanks for contributing to The All ▲lgorithms project, the huge collection of algorithms implemented in different languages.

Before merging the pull request you will need to review the contributing guide because there are changes must be done.

├── allalgorithms
│   │── sorting
|   |    │── bubble_sort.py
|   |    └── merge_sort.py
│   └── searches
|        │── binary_search.py
|        └── linear_search.py
├── docs
│   │── sorting
|   |    │── bubble-sort.md
|   |    └── merge-sort.md
│   └── searches
|        │── binary-search.md
|        └── linear-search.md
└── tests
    │── test_searches.py
    └── test_sorting.py

The above style is required so you may need to add the algorithm along the tests and documentation