feat: revamped oclif-powered docs (#1081)

## 🧰 Changes

Overhauls all of our command docs and creates a new
`documentation/commands/` directory with pages for each of the command
categories.

I took all of the command-specific docs + examples from `README.md` and
moved them into each respective command's code.

## 🧬 QA & Testing

Do all of the docs changes look sound? Is there any loss in information?

<sub>this is an <code>oclif</code> supremacy account</sub>

.alexrc.yml

@@ -1 +1,3 @@
 profanitySureness: 1
+allow:
+  - postman-postwoman

.prettierignore

@@ -7,5 +7,5 @@ coverage/
 # release build artifacts
 CHANGELOG.md
 dist/
-documentation/commands.md
+documentation/commands
 dist-gha/

bin/run.js

@@ -11,7 +11,7 @@ async function main() {
     opts.args = stringArgv(process.env.INPUT_RDME);
   }
   await execute(opts).then(msg => {
-    if (msg) {
+    if (msg && typeof msg === 'string') {
       // eslint-disable-next-line no-console
       console.log(msg);
     }