Fix typos in .gitignore (#1697)

Small fix to some typos that cropped up in the .gitignore with #1676

Authors:
  - Charles Blackmon-Luca (https://github.com/charlesbluca)
  - Lawrence Mitchell (https://github.com/wence-)

Approvers:
  - Lawrence Mitchell (https://github.com/wence-)
  - Mark Harris (https://github.com/harrism)

URL: #1697

.gitignore

@@ -22,13 +22,13 @@ rmm.egg-info/
 python/build
 python/*/build
 python/rmm/docs/_build
-python/rmm/**/librmmm/**/*.cpp
-!python/rmm/librmmm/_torch_allocator.cpp
+python/rmm/**/librmm/**/*.cpp
+!python/rmm/librmm/_torch_allocator.cpp
 python/rmm/**/librmm/**/*.h
 python/rmm/**/librmm/.nfs*
-python/rmm/**/pylibrmmm/**/*.cpp
-python/rmm/**/pylibrmmm/**/*.h
-python/rmm/**/pylibrmmm/.nfs*
+python/rmm/**/pylibrmm/**/*.cpp
+python/rmm/**/pylibrmm/**/*.h
+python/rmm/**/pylibrmm/.nfs*
 python/rmm/_cuda/*.cpp
 python/rmm/tests/*.cpp
 python/rmm/*.ipynb