Update the docs with specifics about escaping of compile commands.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159987 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/JSONCompilationDatabase.html b/docs/JSONCompilationDatabase.html
index 9785ac4..2907194 100644
--- a/docs/JSONCompilationDatabase.html
+++ b/docs/JSONCompilationDatabase.html
@@ -71,7 +71,9 @@
 compiled with different configurations.</li>
 <li><b>command:</b> The compile command executed. After JSON unescaping, this must
 be a valid command to rerun the exact compilation step for the translation unit in
-the environment the build system uses.</li>
+the environment the build system uses. Parameters use shell quoting and shell escaping
+of quotes, with '"' and '\' being the only special characters. Shell expansion is
+not supported.</li>
 </ul>
 </p>