Fix and update docs.

src/bootstrap/Alert.md

@@ -1,4 +1,5 @@
 Bootstrap alert component.
+
 ```jsx
 import {useState} from 'react';
 
@@ -7,14 +8,14 @@ function AlertExample(){
     if (alert)
         return <Alert 
             type='warning' 
-            message='Some warning out there!' 
             onDismiss={()=>setAlert(false)}
-        />;
+        >
+            Some warning out there!        
+        </Alert>;
     return <button 
         className='btn btn-secondary' 
         onClick={()=>setAlert(true)}
     >Show alert again</button>;
 };
 <AlertExample/>
-
 ```

src/bootstrap/FileInput.js

@@ -19,6 +19,8 @@ FileInput.propTypes = {
     helpText: PropTypes.string,
     /** Email value. */
     value: PropTypes.string,
+    /** Allow selecting multiple files. */
+    multiple: PropTypes.bool,
 };
 
 export function FileInput({ ...props }) {

src/bootstrap/FileInput.md

@@ -3,13 +3,39 @@ Bootstrap component for file input. Includes label and has predefined sizes and
 All additional `props` are passed to the `<input type="file">` HTML component.
 
 ```js
-import {useState} from 'react';
+import { useState } from 'react';
+
 const [files, setFiles] = useState([]);
 
-<FileInput
-    files={files}
-    label="Some file"
-    helpText="Will be uploaded"
-    onChange={event =>setFiles(event.target.files)}
-/>
+// Note that files is not an array but FileList.
+const label = files.length === 1 ? files[0].name : "Choose file";
+
+<form className="col">
+    <FileInput
+        files={files}
+        label={label}
+        helpText="Will be uploaded"
+        onChange={event=>setFiles(event.target.files)}
+    />
+</form>
+```
+
+### FileInput with multiple files
+```js
+import { useState } from 'react';
+
+const [files, setFiles] = useState([]);
+
+// Note that files is not an array but FileList.
+const label = files.length > 0 ? Array.from(files).map(file=>file.name).join(", ") : "Choose files";
+
+<form className="col">
+    <FileInput
+        files={files}
+        label={label}
+        helpText="Will be uploaded"
+        onChange={event=>setFiles(event.target.files)}
+        multiple
+    />
+</form>
 ```

src/bootstrap/Modal.md

@@ -6,8 +6,6 @@ it's required to have an element `<div id={"modal-container"}/>` somewhere on th
     <div id="modal-container"/>
 ```
 
-I have no idea why example doesn't work here but you can investigate HTML code and Foris project.
-
 ```js
 import {ModalHeader, ModalBody, ModalFooter} from './Modal';