Misc-typos (#741)

Found in downstream CMake repo via `codespell -q 3`
diff --git a/include/json/config.h b/include/json/config.h
index 9410449..7d34692 100644
--- a/include/json/config.h
+++ b/include/json/config.h
@@ -80,7 +80,7 @@
 
 // In c++11 the override keyword allows you to explicitly define that a function
 // is intended to override the base-class version.  This makes the code more
-// managable and fixes a set of common hard-to-find bugs.
+// manageable and fixes a set of common hard-to-find bugs.
 #if __cplusplus >= 201103L
 # define JSONCPP_OVERRIDE override
 # define JSONCPP_NOEXCEPT noexcept