README.md: minor improvements

Slightly improved the description and build instructions, added required library package name on RPM-based distributions like Fedora/Red Hat.

README.md

@@ -1,33 +1,43 @@
 # googerteller
-audible feedback on just how much your browsing feeds into google
+
+Audible feedback on just how much your browsing feeds into Google.
 
 By [email protected] / https://berthub.eu/
 
 ## How to compile
-First install libpcaudio (libpcaudio-dev), then:
+
+You need a C++ compiler like `gcc-c++` and CMake for compiling the binary.
+
+You also need to install `libpcaudio` (`libpcaudio-dev` on Debian/Ubuntu, `pcaudiolib-devel` on Fedora/Red Hat).
+
+Then run:
 
 ```
 cmake .
 make
 ```
 
-## How to run:
+## How to run
 
 ```
 sudo tcpdump -n -l dst net 192.0.2.1/32 $(for a in $(cat goog-prefixes.txt); do echo or dst net $a; done)  |  ./teller 
 ```
 
+Replace `192.0.2.1` with the IP address of your default gateway (e.g. your Internet router).
+
 And then cry.
 
 ## Problems
-If tcpdump complains about `Warning: Kernel filter failed: Cannot allocate memory`, try
+
+If `tcpdump` complains about `Warning: Kernel filter failed: Cannot allocate memory`, try
 this first:
 
 ```
 sudo sysctl net.core.optmem_max=204800
 ```
 
 ## Data source
+
 The list of Google services IP addresses can be found on [this Google
 support page](https://support.google.com/a/answer/10026322?hl=en).