README: moved usage to docs

Author: ken-matsui

README.md

@@ -88,186 +88,6 @@ Although building from source is not recommended, if you really want to do so, s
 * clang-format (for `poac fmt`)
 * clang-tidy (for `poac tidy`)
 
-## Usage
-
-### Start a new project with Poac
-
-The `poac new` command lets you start a new Poac project:
-
-```console
-you:~$ poac new hello_world
-     Created binary (application) `hello_world` package
-```
-
-> [!TIP]
-> If you want to integrate your existing project with Poac, use the `init` command:
->
-> ```console
-> you:~/your-pj$ poac init
->      Created binary (application) `your-pj` package
-> ```
->
-> This command just creates a `poac.toml` file not to break your project.
-
-### Build the project
-
-In most cases, you want to execute the generated binary as well as build the project.
-
-```console
-you:~/hello_world$ poac run
- Compiling src/main.cc
-   Linking hello_world
-  Finished debug target(s) in 0.45386s
-   Running poac-out/debug/hello_world
-Hello, world!
-```
-
-If you just want to build it, run the `build` command:
-
-```console
-you:~/hello_world$ poac build
-  Finished debug target(s) in 0.00866317s
-```
-
-Poac uses a cache since we executed the command with no changes.
-
-> [!TIP]
-> To use a different compiler, you can export a `CXX` environmental variable:
->
-> ```shell
-> export CXX=g++-13
-> ```
-
-### Install dependencies
-
-Like Cargo does, Poac installs dependencies at build time.  Poac currently supports Git and system dependencies.  You can use the `poac add` command to add dependencies to your project.
-
-The `poac add` command accepts the following arguments:
-
-`poac add <package names ....> --<options>`
-
-Options:
-- `--sys`: Marks the packages as system dependency (requires the `--version` argument)
-- `--version`: Specify dependency version. Only used with system dependencies
-- `--rev`: Specify revision for git dependencies
-- `--tag`: Specify tag for git dependencies
-- `--branch`: Specify branch for git dependencies
-
-Example
-```bash
-poac add libgit2 --sys --version "1.1.0"
-poac add "ToruNiina/toml11" --rev "846abd9a49082fe51440aa07005c360f13a67bbf"
-```
-
-If `tag`, `branch`, or `rev` is unspecified for git dependencies, Poac will use the latest revision of the default branch. System dependency names must be acceptable by `pkg-config`. The version requirement syntax is specified in [src/VersionReq.hpp](https://github.com/poac-dev/poac/blob/main/src/VersionReq.hpp).
-
-After adding dependencies, executing the `build` command will install the package and its dependencies.
-
-```console
-you:~/hello_world$ poac build
-Downloaded ToruNiina/toml11 846abd9a49082fe51440aa07005c360f13a67bbf
- Compiling src/main.cc
-   Linking hello_world
-  Finished debug target(s) in 0.70s
-```
-
-> [!WARNING]
-> Poac currently supports building a project with header-only dependencies.
-> Building with build-required dependencies will be soon supported.
-
-### Unit tests
-
-You can write unit tests in any source files within the `src` directory.  Create a new file like:
-
-`src/Lib.cc`
-
-```cpp
-int add(int a, int b) {
-  return a + b;
-}
-
-#ifdef POAC_TEST
-
-#  include <cassert>
-
-int main() {
-  assert(add(1, 2) == 3);  // ok
-  assert(add(1, 2) == 4);  // fail
-}
-
-#endif
-```
-
-Now, with the `test` command, you can run tests defined within `POAC_TEST`:
-
-```console
-you:~/hello_world$ poac test
- Compiling src/Lib.cc
-   Linking tests/test_Lib
-   Testing Lib
-Assertion failed: (add(1, 2) == 4), function main, file Lib.cc, line 13.
-make: *** [test] Abort trap: 6
-```
-
-Unit tests with the `POAC_TEST` macro are useful when testing private functions.  Integration testing with the `tests` directory has not yet been implemented.
-
-### Run linter
-
-Linting source code is essential to protect its quality.  Poac supports linting your project by the `lint` command:
-
-```console
-you:~/hello_world$ poac lint
-   Linting hello_world
-src/main.cc:0:  No copyright message found.  You should have a line: "Copyright [year] <Copyright Owner>"  [legal/copyright] [5]
-Done processing src/main.cc
-Total errors found: 1
-Error: `cpplint` exited with status 1
-```
-
-> [!TIP]
-> If you do not have `cpplint`, install it with the following command:
->
-> ```bash
-> pip install cpplint
-> ```
-
-The `lint` command works without configurations, and Poac would automatically opt out of unwanted lints by adjusting to each project.
-To customize the lint settings, try adding the `[lint.cpplint]` key in your `poac.toml` like [this](https://github.com/poac-dev/poac/blob/cc30b706fb49860903384df56d650a0955aca16c/poac.toml#L67-L83)
-or creating a [`CPPLINT.cfg`](https://github.com/poac-dev/poac/blob/5e7e3792e8818d165149214e94f30958fb0fef66/CPPLINT.cfg) file in the repository root.
-
-### Run formatter
-
-Poac also supports formatting your source code with `clang-format`.  Ensure having installed `clang-format` before running this command.
-
-```console
-you:~/hello_world$ poac fmt
-  Formatting hello_world
-```
-
-> [!NOTE]
-> This command automatically detects what files we need to format to avoid getting bothered by commands like:
->
-> ```console
-> $ # We need to avoid the `build` dir and such dirs ...
-> $ clang-format ./src/*.cpp -i
-> $ clang-format ./include/**/*.hpp -i
-> $ clang-format ./tests/**/*.cpp -i
-> $ ...
-> ```
-
-To customize the format settings, try creating a [`.clang-format`](/.clang-format) file to the repository root.
-
-### Run `clang-tidy`
-
-Poac also supports running `clang-tidy` on your source code.  Ensure having installed `clang-tidy` before running this command.
-
-```console
-you:~/hello_world$ poac tidy
-  Running clang-tidy
-```
-
-You can customize the tidy settings by creating a [`.clang-tidy`](/.clang-tidy) file to the repository root.
-
 ## Community
 
 We use [GitHub Discussions](https://github.com/orgs/poac-dev/discussions).