add: [workshops] bib file to hold workshops references

docs/workshop/references.bib

@@ -0,0 +1,10 @@
+% Encoding: UTF-8
+
+@Book{seriouscrypto,
+  title     = {Serious Cryptography: A Practical Introduction to Modern Encryption},
+  publisher = {no starch press},
+  year      = {2017},
+  author    = {Jean-Philippe Aumasson},
+}
+
+@Comment{jabref-meta: databaseType:bibtex;}