Fix some broken documentation comments

Summary: I temporarily enabled Clang's `-Wdocumentation` flag, which reports things like using an `param` for a parameter that doesn't exist. [Full explanation with examples here](https://clang.llvm.org/docs/DiagnosticsReference.html#wdocumentation).

Reviewed By: yfeldblum

Differential Revision: D21396362

fbshipit-source-id: d7b34bc14af7bb1b0901a8f195c02674eb587fbc

folly/IPAddress.h

@@ -178,7 +178,7 @@ class IPAddress {
 
   /**
    * Return a string representation of a CIDR block created with createNetwork.
-   * @param [in] network, pair of address and cidr
+   * @param [in] network pair of address and cidr
    *
    * @return string representing the netblock
    */
@@ -326,7 +326,7 @@ class IPAddress {
    *
    * @note This is slower than the below counterparts. If perf is important use
    *       one of the two argument variations below.
-   * @param [in] ipSlashCidr address in "192.168.1.0/24" format
+   * @param [in] cidrNetwork address in "192.168.1.0/24" format
    * @throws IPAddressFormatException if no /mask
    * @return true if address is part of specified subnet with cidr
    */