Merge pull request rapid7#1278 from kernelsmith/gitignore

change doc to doc/ in .gitignore

Author: HD Moore

.gitignore

@@ -10,7 +10,7 @@
 coverage
 data/meterpreter/ext_server_pivot.dll
 data/meterpreter/ext_server_pivot.x64.dll
-doc
+doc/
 external/source/meterpreter/java/bin
 external/source/meterpreter/java/build
 external/source/meterpreter/java/extensions