docs: add Slack CLI setup instructions to README.md

[srtaalej]

Summary

• Adds collapsible "Using Slack CLI" and "Using Terminal" sections to the installation guide
• Matches the pattern used by bolt-python-assistant-template and bolt-python-search-template

Test plan

• Verify rendered README displays both collapsible sections correctly and commands are accurate

[WilliamBergamin]

Nice 💯

[zimeg]

🪝 We might want to include the hooks package as part of pyproject.toml alongside this too?

[slack-samples]

$ slack create -t slack-samples/bolt-python-starter-template -b add-slack-cli-instructions

[zimeg]

🎁 A few more comments on streamlining setups and stable packages!

[zimeg]

🔬 suggestion: We should pick one of these options of versioning? I'd suggest exact pins because @dependabot should be checking back often!

[zimeg]

Suggested change

	#### Creating the Slack app
	Use the following command to add your new Slack app to your development workspace. Choose a "local" app environment for upcoming development:
	```sh
	slack install
	```
	After the Slack app has been created you're all set to start developing!

🪓 question: Might we remove this in favor of the run command installs?

[zimeg]

🪬 Leaving a note that we might want to separate CLI support from improved packaging!

[zimeg]

(.venv) $ pip install .
Processing /Users/eden.zimbelman/programming/samples/bolt-python-starter-template
  Installing build dependencies ... done
  Getting requirements to build wheel ... error
  error: subprocess-exited-with-error

  × Getting requirements to build wheel did not run successfully.
  │ exit code: 1
  ╰─> [14 lines of output]
      error: Multiple top-level packages discovered in a flat-layout: ['logs', 'listeners'].

      To avoid accidental inclusion of unwanted files or directories,
      setuptools will not proceed with this build.

      If you are trying to create a single distribution with multiple packages
      on purpose, you should not rely on automatic discovery.
      Instead, consider the following options:

      1. set up custom discovery (`find` directive with `include` or `exclude`)
      2. use a `src-layout`
      3. explicitly set `py_modules` or `packages` with a list of names

      To find more information, look for "package discovery" on setuptools docs.
      [end of output]

  note: This error originates from a subprocess, and is likely not a problem with pip.

[notice] A new release of pip is available: 24.3.1 -> 26.1.1
[notice] To update, run: pip install --upgrade pip
error: subprocess-exited-with-error

× Getting requirements to build wheel did not run successfully.
│ exit code: 1
╰─> See above for output.

note: This error originates from a subprocess, and is likely not a problem with pip.

⚠️ issue: This might find conflict in new virtual environments? I'm wondering if we want to keep these changes focused to requirements.txt in this PR and follow up to favor pyproject.toml afterward

[srtaalej]

ah thanks for catching that! will do 🫡