Updated .gitignore to be more specific

Author: Ryan van Polen

.gitignore

@@ -1,4 +1,17 @@
+# This file only excludes files that are specific to this repository. Please setup your own global 
+# `.gitignore` file to exclude files that are specific to your operating system and IDE.
+# 
+# From https://git-scm.com/docs/gitignore:
+# 
+# > Patterns which a user wants Git to ignore in all situations (e.g., backup or temporary files 
+# > generated by the user’s editor of choice) generally go into a file specified by 
+# > `core.excludesFile` in the user’s `~/.gitconfig`.
+# 
+# Discussed in PR https://github.com/rustls/rcgen/pull/342
+
+# Rust and Cargo
 /target
 **/*.rs.bk
+
+# Project
 certs/
-.idea