Fix typo error
- README.md
**Self-evaluation:**
1. Build test: [X]Passed [ ]Failed [ ]Skipped
2. Run test: [X]Passed [ ]Failed [ ]Skipped
Signed-off-by: Donghyeon Jeong <dhyeon.jeong@samsung.com>
| sgd | Stochastic Gradient Decent | - |
| adam | Adaptive Moment Estimation | - |
- | Keyword | Leanring Rate | Description |
+ | Keyword | Learning Rate | Description |
|:-------:|:---:|:---:|
| exponential | exponential learning rate decay | - |
| constant | constant learning rate | - |