[repo][docs] Reorganize the repo + update the readme file (#46)

This pull request includes significant updates to the `README.md` file
and several changes to benchmark files, mainly focusing on improving
documentation and code organization.

### Documentation Enhancements:
- **README.md**: Expanded the overview and added detailed descriptions
of the `Decimal` type and future roadmap items. Enhanced the
installation instructions and added a comprehensive quick-start guide.
- **Status Section**: Updated the status of the project phases,
detailing the completion of the "Make it Work" phase, progress in the
"Make it Right" phase, and significant advancements in the "Make it
Fast" phase. Added a new "Future Extensions" section.
- **Footnotes**: Added footnotes to explain the fixed precision and
arbitrary precision types, providing context and comparisons to similar
implementations in other languages.

### Codebase organization:
- **Dedicated folder for Decimal type**: Added a dedicated `decimal`
sub-package for the `Decimal` type. Also added dedicated folders for the
tests and benches.

Author: forfudan

.github/workflows/run_tests.yaml

@@ -55,10 +55,9 @@ jobs:
           cp decimojo.mojopkg tests/
           cp decimojo.mojopkg benches/
 
-      - name: Run tests and benches
+      - name: Run tests
         run: |
           magic run mojo test tests
-          magic run bench
 
       - name: Install pre-commit
         run: |

README.md

@@ -73,7 +73,7 @@ fn run_benchmark(
     var py_decimal = pydecimal.Decimal(input_value)
 
     # Execute the operations once to verify correctness
-    var mojo_result = dm.exponential.exp(mojo_decimal)
+    var mojo_result = mojo_decimal.exp()
     var py_result = py_decimal.exp()
 
     # Display results for verification
@@ -83,7 +83,7 @@ fn run_benchmark(
     # Benchmark Mojo implementation
     var t0 = perf_counter_ns()
     for _ in range(iterations):
-        _ = dm.exponential.exp(mojo_decimal)
+        _ = mojo_decimal.exp()
     var mojo_time = (perf_counter_ns() - t0) / iterations
     if mojo_time == 0:
         mojo_time = 1  # Prevent division by zero