docs: enhance validation guide with tip on preventing submission when form is untouched (#1814)

* Enhance validation guide with preventing submission tip

Added guidance on preventing form submission before interaction.

* move the tip after the code block to no break logic

* enhance guide for all frameworks

Author: kostyniuk

docs/framework/angular/guides/validation.md

@@ -688,3 +688,5 @@ export class AppComponent {
   // ...
 }
 ```
+
+To prevent the form from being submitted before any interaction, combine `canSubmit` with `isPristine` flags. A simple condition like `!canSubmit || isPristine` effectively disables submissions until the user has made changes.

docs/framework/lit/guides/validation.md

@@ -629,3 +629,5 @@ class MyForm extends LitElement {
   }
 }
 ```
+
+To prevent the form from being submitted before any interaction, combine `canSubmit` with `isPristine` flags. A simple condition like `!canSubmit || isPristine` effectively disables submissions until the user has made changes.

docs/framework/react/guides/validation.md

@@ -559,3 +559,5 @@ return (
   />
 )
 ```
+
+To prevent the form from being submitted before any interaction, combine `canSubmit` with `isPristine` flags. A simple condition like `!canSubmit || isPristine` effectively disables submissions until the user has made changes.

docs/framework/solid/guides/validation.md

@@ -564,3 +564,5 @@ return (
   />
 )
 ```
+
+To prevent the form from being submitted before any interaction, combine `canSubmit` with `isPristine` flags. A simple condition like `!canSubmit || isPristine` effectively disables submissions until the user has made changes.

docs/framework/svelte/guides/validation.md

@@ -404,3 +404,5 @@ You can subscribe to it via `form.Subscribe` and use the value in order to, for
   {/snippet}
 </form.Subscribe>
 ```
+
+To prevent the form from being submitted before any interaction, combine `canSubmit` with `isPristine` flags. A simple condition like `!canSubmit || isPristine` effectively disables submissions until the user has made changes.

docs/framework/vue/guides/validation.md

@@ -583,3 +583,5 @@ const form = useForm(/* ... */)
   <!-- ... -->
 </template>
 ```
+
+To prevent the form from being submitted before any interaction, combine `canSubmit` with `isPristine` flags. A simple condition like `!canSubmit || isPristine` effectively disables submissions until the user has made changes.