Adding link to unsafe features documentation

app/build.gradle

@@ -14,8 +14,8 @@ android {
         applicationId "sushi.hardcore.droidfs"
         minSdkVersion 21
         targetSdkVersion 29
-        versionCode 4
-        versionName "1.1.9"
+        versionCode 5
+        versionName "1.1.10"
 
         android.ndkVersion = "21.2.6472646"
         ndk {

app/src/main/res/drawable/icon_notes.xml

@@ -0,0 +1,5 @@
+<vector android:height="24dp" android:tint="#FFFFFF"
+    android:viewportHeight="24" android:viewportWidth="24"
+    android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="@android:color/white" android:pathData="M3,18h12v-2L3,16v2zM3,6v2h18L21,6L3,6zM3,13h18v-2L3,11v2z"/>
+</vector>

app/src/main/res/values/strings.xml

@@ -180,4 +180,6 @@
     <string name="key_permanently_invalidated_exception">KeyPermanentlyInvalidatedException</string>
     <string name="key_permanently_invalidated_exception_msg">It looks like you have added a new fingerprint. Saved passwords hash have become unusable.</string>
     <string name="no_more_images">No more images found.</string>
+    <string name="usf_read_doc">You should read it carefully before enabling any of these options.</string>
+    <string name="usf_doc">Unsafe features documentation</string>
 </resources>

app/src/main/res/xml/unsafe_features_preferences.xml

@@ -50,4 +50,16 @@
 
     </PreferenceCategory>
 
+    <PreferenceCategory
+        android:title="@string/about">
+
+        <Preference
+            android:title="@string/usf_doc"
+            android:summary="@string/usf_read_doc"
+            android:icon="@drawable/icon_notes">
+            <intent android:action="android.intent.action.VIEW" android:data="https://github.com/hardcore-sushi/DroidFS#unsafe-features"/>
+        </Preference>
+
+    </PreferenceCategory>
+
 </PreferenceScreen>