update readme

BUILDING.md

@@ -4,22 +4,21 @@ Get the source and install the requirements:
 $ git clone https://github.com/seird/gotify-tray.git
 $ cd gotify-tray
 $ pip install -r requirements.txt
+$ pip install pyinstaller
+```
+
+Currently it's only possible to create installer packages from the pyinstaller output. For any target platform, first create the executable with pyinstaller:
+
+```shell
+$ pyinstaller gotify-tray.spec
 ```
 
 
 # Windows
 
-## Create a stand-alone executable with pyinstaller
-
-```shell
-$ pip install pyinstaller
-$ pyinstaller gotify-tray.spec
-```
-An executable is created at `dist/gotify-tray/`.
-
 ## Create an installer with Inno Setup
 
-Create an installer for windows with inno setup from pyinstaller output:
+Create an installer for windows with [inno setup](https://github.com/jrsoftware/issrc) from pyinstaller output:
 
 ```shell
 $ iscc gotify-tray.iss
@@ -30,14 +29,21 @@ The installer is created at `inno-output/gotify-tray-installer.exe`.
 
 # Linux
 
+Packages can be created from the pyinstaller output with [fpm](https://fpm.readthedocs.io/). Run the `build_linux.sh` script with the desired package type:
+
 ## Create a deb package
 
+
 ```shell
-$ make build
+$ ./build_linux.sh deb
+```
 
-# or install
 
-$ sudo make install
+## Create a pacman package
+
+
+```shell
+$ ./build_linux.sh pacman
 ```
 
 
@@ -59,7 +65,7 @@ $ pyinstaller gotify-tray.spec
 
 - Install the pip package:
     ```shell
-    $ pip install dist/gotify_tray-0.1.14-py3-none-any.whl
+    $ pip install dist/gotify_tray-{{VERSION}}-py3-none-any.whl
     ```
 
 - Launch from the command line: