README: refine wordings (minor)

Author: ickc

README.md

@@ -8,9 +8,9 @@ In the [releases page](https://github.com/pandoc-extras/pandoc-portable/releases
 
 The versions of the script and travis setup in this repository will be in this `README.md` file. Current version: 0.1
 
-# Security Concern
+# Security
 
-The nice thing about this setup is nothing is done privately. e.g. none of the binaries goes through my computer. The main scripts are `.travis.yml` and `pandocDownload2zip.sh`, which is open source. The builds happened on Travis, where all build history is in the open. Feel free to audit (and contribute).
+The nice thing about this setup is nothing is done privately. e.g. none of the binaries goes through my computer. The main scripts are `.travis.yml` and `pandocDownload2zip.sh`, which is open source. The builds happened on Travis, where all build history is in the open. Feel free to audit.
 
 # License