docs: document when-then + migrations revert change (#8089)

- Add documentation around when-then and workflow conditions
- Change the CLI reference based on change in revert migrations command.

www/apps/book/app/advanced-development/workflows/conditions/page.mdx

@@ -0,0 +1,62 @@
+export const metadata = {
+  title: `${pageNumber} Conditions in Workflow with When-Then`,
+}
+
+# {metadata.title}
+
+In this chapter, you'll learn how to execute an action based on a condition in a workflow using the when-then utility.
+
+## What is the When-Then Utility?
+
+The when-then utility executes an action if a condition is satisfied.
+
+Since if-conditions aren't allowed in the workflow constructor function, use the when-then utility if you want to execute a step based on a condition.
+
+---
+
+## How to Use the When-Then Utility?
+
+For example:
+
+export const highlights = [
+  ["15", "input", "The data to pass as a parameter to the function in the second parameter"],
+  ["17", "return", "The function must return a boolean value indicating whether\nthe callback function passed to `then` should be executed."],
+  ["19", "() => {", "The function to execute if `when`'s second parameter returns a `true` value."]
+]
+
+```ts highlights={highlights}
+import { 
+  createWorkflow,
+  when
+} from "@medusajs/workflows-sdk"
+// step imports...
+
+type WorkflowInput = {
+  is_active: boolean
+}
+
+const workflow = createWorkflow
+  <WorkflowInput, any>
+  ("workflow", function (input) {
+    const result = when(
+      input, 
+      (input) => {
+        return input.is_active
+      }
+    ).then(() => {
+      const stepResult = isActiveStep()
+      return stepResult
+    })
+
+    // executed without condition
+    return anotherStep(result)
+  }
+)
+```
+
+Then `when` utility is a function imported from `@medusajs/workflows-sdk`. It accepts the following parameters:
+
+1. An object or the workflow's input. This data is passed as a parameter to the function in `when`'s second parameter.
+2. A function that returns a boolean indicating whether to execute the action.
+
+To specify the action to perform if the condition is satisfied, chain a `then` function to `when` and pass it a callback function. The callback function is only executed if `when`'s second parameter function returns a `true` value.

www/apps/book/app/advanced-development/workflows/constructor-constraints/page.mdx

@@ -75,6 +75,35 @@ const myWorkflow = createWorkflow<
 })
 ```
 
+### No If Conditions
+
+You can't use if-conditions in a workflow. Instead, use the when-then utility function explained in the next chapter:
+
+```ts
+// Don't
+const myWorkflow = createWorkflow<
+  WorkflowInput,
+  WorkflowOutput
+>("hello-world", function (input) {
+  if (input.is_active) {
+    // perform an action
+  }
+})
+
+// Do (explained in the next chapter)
+const myWorkflow = createWorkflow<
+  WorkflowInput,
+  WorkflowOutput
+>("hello-world", function (input) {
+  when(input, (input) => {
+    return input.is_active
+  })
+  .then(() => {
+    // perform an action
+  })
+})
+```
+
 ---
 
 ## Step Constraints

www/apps/book/sidebar.mjs

@@ -191,6 +191,10 @@ export const sidebar = sidebarAttachHrefCommonOptions(
               path: "/advanced-development/workflows/constructor-constraints",
               title: "Workflow Constraints",
             },
+            {
+              path: "/advanced-development/workflows/conditions",
+              title: "Conditions in Workflows",
+            },
             {
               path: "/advanced-development/workflows/compensation-function",
               title: "Compensation Function",

www/apps/resources/app/medusa-cli/page.mdx

@@ -340,12 +340,20 @@ npx medusa start
   </Table.Body>
 </Table>
 
-### migrations
+### migrations run
 
-Perform migration actions to reflect changes on the database, such as running or reverting migrations.
+Run the latest migrations to reflect changes on the database.
 
 ```bash
-npx medusa migrations <action>
+npx medusa migrations run
+```
+
+### migration revert
+
+Revert the last migrations ran on one or more modules.
+
+```bash
+npx medusa migrations revert <module_names...>
 ```
 
 #### Arguments
@@ -362,15 +370,12 @@ npx medusa migrations <action>
     <Table.Row>
       <Table.Cell>
       
-      `action`
+      `module_names`
       
       </Table.Cell>
       <Table.Cell>
 
-      The action to perform. Values can be `run`, `show`, or `revert`.
+      The name of one or more module, separated by spaces. For example, `helloModuleService`.
-      `run` is used to run the migrations; `show` is used to only show 
-      what migrations are available to run; and `revert` is to undo the 
-      last migration.
       
       </Table.Cell>
       <Table.Cell>