Pairwise Swap in Linked List

**Is your feature request related to a problem? Please describe.**
Pairwise Swap (Linked List)

**Describe the solution you'd like**
It is implemented using Linked List in C Language.

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Additional context**
Add any other context or screenshots about the feature request here.

### Programming language

- [ ] C
- [ ] C++
- [ ] Java
- [ ] Python