Fix broken links inside app

Summary:
Searched for broken link patterns inside the app itself. I think I found them all but it's not certain.

Patterns searched for and replaced:
```
.html
getting-started/)
getting-started)
getting-started"
```

and also searched the repo for regex `\]\(.*)` and checked them by eye.

Reviewed By: passy

Differential Revision: D21306944

fbshipit-source-id: a2e09b0fd8677f5f26e5cc4a06805b474247f7e6

desktop/app/src/MenuBar.tsx

@@ -365,15 +365,15 @@ function getTemplate(
         {
           label: 'Getting started',
           click: function () {
-            shell.openExternal('https://fbflipper.com/docs/getting-started/');
+            shell.openExternal(
+              'https://fbflipper.com/docs/getting-started/index',
+            );
           },
         },
         {
           label: 'Create plugins',
           click: function () {
-            shell.openExternal(
-              'https://fbflipper.com/docs/tutorial/intro.html',
-            );
+            shell.openExternal('https://fbflipper.com/docs/tutorial/intro');
           },
         },
         {

desktop/app/src/chrome/WelcomeScreen.tsx

@@ -138,9 +138,7 @@ export default class WelcomeScreen extends PureComponent<Props, State> {
           <Item
             onClick={() =>
               shell &&
-              shell.openExternal(
-                'https://fbflipper.com/docs/features/index.html',
-              )
+              shell.openExternal('https://fbflipper.com/docs/features/index')
             }>
             <Icon size={20} name="rocket" color={brandColors.Flipper} />
             <FlexColumn>
@@ -153,9 +151,7 @@ export default class WelcomeScreen extends PureComponent<Props, State> {
           <Item
             onClick={() =>
               shell &&
-              shell.openExternal(
-                'https://fbflipper.com/docs/tutorial/intro.html',
-              )
+              shell.openExternal('https://fbflipper.com/docs/tutorial/intro')
             }>
             <Icon size={20} name="magic-wand" color={brandColors.Flipper} />
             <FlexColumn>
@@ -166,7 +162,9 @@ export default class WelcomeScreen extends PureComponent<Props, State> {
           <Item
             onClick={() =>
               shell &&
-              shell.openExternal('https://fbflipper.com/docs/getting-started/')
+              shell.openExternal(
+                'https://fbflipper.com/docs/getting-started/index',
+              )
             }>
             <Icon size={20} name="tools" color={brandColors.Flipper} />
             <FlexColumn>

desktop/app/src/chrome/plugin-manager/PluginDebugger.tsx

@@ -218,7 +218,7 @@ class PluginDebugger extends Component<Props> {
           emulator/simulator currently running on your system, or is there a
           development device connected via USB? There are some devices/emulators
           known to have problems connecting to Flipper. Check out the{' '}
-          <Link href="https://fbflipper.com/docs/troubleshooting.html#known-incompatibilities">
+          <Link href="https://fbflipper.com/docs/troubleshooting#known-incompatibilities">
             known incompatibilities
           </Link>
           .
@@ -249,7 +249,7 @@ class PluginDebugger extends Component<Props> {
           <InfoText>
             To debug why Flipper couldn't establish a connection to the app,
             check out our documentation about{' '}
-            <Link href="https://fbflipper.com/docs/troubleshooting.html#connection-issues">
+            <Link href="https://fbflipper.com/docs/troubleshooting#connection-issues">
               connection issues
             </Link>
             .

desktop/pkg/src/commands/lint.ts

@@ -35,7 +35,7 @@ export default class Lint extends Command {
       const errors = await runLint(inputDirectory);
       if (errors) {
         this.error(
-          `Plugin package definition is invalid. See https://fbflipper.com/docs/extending/js-setup.html#plugin-definition for details.\n${errors.join(
+          `Plugin package definition is invalid. See https://fbflipper.com/docs/extending/js-setup#plugin-definition for details.\n${errors.join(
             '\n',
           )}`,
         );

desktop/plugins/rn-tic-tac-toe/index.tsx

@@ -124,9 +124,7 @@ export default class ReactNativeTicTacToe extends FlipperPlugin<
           <Info type="info">
             This plugin demonstrates how to create pure JavaScript Flipper
             plugins for React Native. Find out how to create a similar plugin at{' '}
-            <a
-              href="https://fbflipper.com/docs/tutorial/intro.html"
-              target="blank">
+            <a href="https://fbflipper.com/docs/tutorial/intro" target="blank">
               fbflipper.com
             </a>
             .