ci: update deployment for doc rearrangement

This fixes CI to handle the new documentation files. We also continue to
do more cleanup. In particular, we devise a nicer way of detecting the
most recent Cargo OUT_DIR by writing a dummy file, and looking for the
most recently modified version of that file.

.gitignore

@@ -6,6 +6,7 @@ target
 /ignore/Cargo.lock
 /termcolor/Cargo.lock
 /wincolor/Cargo.lock
+/deployment
 
 # Snapcraft files
 stage
@@ -13,4 +14,4 @@ prime
 parts
 *.snap
 *.pyc
-ripgrep*_source.tar.bz2
+ripgrep*_source.tar.bz2