chore: README update

README.adoc

@@ -23,9 +23,17 @@ tebako-runtime (this Gem) provides support for known Gems that use system calls
 
 == Supported Gems
 
+* https://rubygems.org/gems/excavate/[excavate]
 * https://rubygems.org/gems/ffi[ffi]
+* https://rubygems.org/gems/jing[jing]
 * https://rubygems.org/gems/mn2pdf[mn2pdf]
 * https://rubygems.org/gems/mnconvert[mnconvert]
 * https://rubygems.org/gems/ruby-jing[ruby-jing]
 * https://rubygems.org/gems/sassc[sassc]
 * https://rubygems.org/gems/seven-zip[seven-zip]
+
+== Additional features
+In addition to gem support tebako-runtime provides a set of utilities to help with tebako image creation:
+
+* Embedded root SSL certificates's bundle
+* https://rubygems.org/gems/ffi-compiler[ffi-compiler], https://rubygems.org/gems/ffi-compiler2[ffi-compiler2] support