docs: Add some title to examples

Signed-off-by: Alan Clucas <alan@clucas.org>

docs/walk-through/loops.md

@@ -9,6 +9,7 @@ There are two basic ways of running a template multiple times.
     - a JSON object where each element in the object can be addressed by it's key as '{{item.key}}'
 - `withParams` takes a JSON array of items, and iterates over it - again the items can be objects like with `withItems`. This is very powerful, as you can generate the JSON in another step in your workflow, so creating a dynamic workflow.
 
+## `withItems` basic example
 This example is the simplest. We are taking a basic list of items and iterating over it with `withItems`. It is limited to one varying field for each of the workflow templates instantiated.
 
 ```yaml
@@ -41,6 +42,7 @@ spec:
       args: ["{{inputs.parameters.message}}"]
 ```
 
+## `withItems` more complex example
 If we'd like to pass more than one piece of information in each workflow, you can instead use a JSON object for each entry in `withItems` and then address the elements by key, as shown in this example.
 
 ```yaml
@@ -80,6 +82,7 @@ spec:
       args: [/etc/os-release]
 ```
 
+## `withParams` example
 This example does exactly the same job as the previous example, but using `withParam` to pass the information as a JSON array argument, instead of hard-coding it into the template.
 
 ```yaml
@@ -128,6 +131,7 @@ spec:
       args: [/etc/os-release]
 ```
 
+## `withParams` example from another step in the workflow
 Finally, the most powerful form of this is to generate that JSON array of objects dynamically in one step, and then pass it to the next step so that the number and values used in the second step are only calculated at runtime.
 
 ```yaml