change code block lang to svelte

only where it's appropriate

README.md

@@ -20,7 +20,7 @@ Svelte Language Tools contains a library implementing the Language Server Protoc
 
 A `.svelte` file would look something like this:
 
-```html
+```svelte
 <script>
     let count = 1;
 

docs/internal/overview.md

@@ -30,7 +30,7 @@ Our `language-server` can roughly be split into [four areas](/packages/language-
 The last area, TS/JS, is where most of the work is done. Svelte is a mix of JavaScript/TypeScript inside `script` and more of it within Svelte's template syntax. To get a holistic view of the file, we need to account for both.
 This is also the reason why preprocessors such as `svelte-preprocess` cannot do type checking because it produces wrong diagnostics. To preprocess the script content, it only gets the content from the script. Think of this situation:
 
-```html
+```svelte
 <script lang="ts">
     let a: number = 1;
 </script>
@@ -64,7 +64,7 @@ This example shows how our `language-server` uses `svelte2tsx`:
 
 1. Svelte file comes in
 
-```html
+```svelte
 <script>
     export let world = 'name';
 </script>

docs/preprocessors/in-general.md

@@ -17,7 +17,7 @@ module.exports = {
 
 It's also necessary to add a `type="text/language-name"` or `lang="language-name"` to your `style` and `script` tags, which defines how that code should be interpreted by the extension.
 
-```html
+```svelte
 <div>
     <h1>Hello, world!</h1>
 </div>

docs/preprocessors/scss-less.md

@@ -35,7 +35,7 @@ module.exports = {
 
 To gain syntax highlighing for your SCSS code and to make us understand the language you are using, add a `type` or `lang` attribute to your style tags like so:
 
-```html
+```svelte
 <!-- Add type="text/scss" -->
 <style type="text/scss">
     header {

docs/preprocessors/typescript.md

@@ -14,7 +14,7 @@ Adding it to an existing project? [The official blog post explains how to do it]
 
 To tell us to treat your script tags as typescript, add a `type` or `lang` attribute to your script tags like so:
 
-```html
+```svelte
 <!-- Add type="text/typescript" -->
 <script type="text/typescript">
     export let name: string;
@@ -48,7 +48,7 @@ When you are using TypeScript, you can type which events your component has in t
 
 The first and possibly most often used way is to type the `createEventDispatcher` invocation like this:
 
-```html
+```svelte
 <script lang="ts">
     import { createEventDispatcher } from 'svelte';
 
@@ -78,7 +78,7 @@ Make sure to follow the [setup instructions](/packages/svelte-vscode#setup)
 
 The following code may throw an error like `Variable 'show' implicitly has type 'any' in some locations where its type cannot be determined.`, if you have stricter type settings:
 
-```html
+```svelte
 <script lang="typescript">
     export let data: { someKey: string | null };