updated webapp installation instructions

Installation as webapp.md

@@ -6,6 +6,27 @@ Trilium as web application is typically used as a [[sync|Synchronization]] serve
 
 Trilium is a [node.js](http://nodejs.org/) application. Supported version is 8.2.1 and up, but it might work with earlier versions, it's just not tested. It will definitely not run on node version lower than 7.6 though (first version with async/await enabled).
 
+You can check your node version with this command (node.js needs to be installed):
+~~~~
+node --version
+~~~~
+
+If your linux distribution has only outdated version of node.js, you can take a look at the [[installation instructions|https://nodejs.org/en/download/package-manager/#debian-and-ubuntu-based-linux-distributions]] on node.js website which covers most popular distributions.
+
+### Image requirements
+
+To compile libraries required for image support you need to have "autoconf" installed. In ubuntu you can do this with
+
+~~~~
+sudo apt install autoconf
+~~~~
+
+To work with PNG files you'll also need libpng16-16 library.
+
+~~~~
+sudo apt install libpng16-16
+~~~~
+
 ## Installation 
 
 ### Download
@@ -28,3 +49,4 @@ cd trilium
 nohup node bin/www &
 ~~~~
 
+Application by default starts up on port 8080, so you can open your browser and navigate to http://localhost:8080 to access Trilium (replace "localhost" with your hostname).

Keyboard shortcuts.md

@@ -54,5 +54,6 @@ These are hooked in Electron to be similar to native browser keyboard shortcuts.
 * ```ALT+O``` - show SQL console (use only if you know what you're doing)
 * ```ALT+M``` - distraction-free mode - display only note editor, everything else is hidden
 * ```ALT+H``` - show note history
-* ```ALT+S``` - toggle search form in tree pane
+* ```CTRL+S``` - toggle search form in tree pane
 * ```ALT+R``` - show recent changes dialog
+* ```ALT+A``` - show note attributes dialog

Protected notes.md

@@ -42,6 +42,6 @@ Not encrypted:
     * here we use scrypt for [key stretching](https://en.wikipedia.org/wiki/Key_stretching)
 4. Hash produced in the last step is used to decrypt actual _data encryption key_
     * data encryption key is encrypted with [AES-128](https://en.wikipedia.org/wiki/Advanced_Encryption_Standard) with random [IV](https://en.wikipedia.org/wiki/Initialization_vector)
-    * data encryption key is random key generated at the time of [[document|Document]] initialization and is constant over the lifetime of the document. If we change password, only we re-encrypt only this key.
+    * data encryption key is random key generated at the time of [[document|Document]] initialization and is constant over the lifetime of the document. If we change password, we re-encrypt only this key.
 5. We use data encryption key to decrypt actual data - note title and content.
     * encryption used is again AES-128 with [CBC chaining](https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation). IV is primary key (noteId for notes and noteHistoryId for history items)