Fix some -Wdocumentation errors in folly

Summary:
Fixes a few documentation errors that get surfaced when compiling with the -Wdocumentation flag.
Full explanation of errors with examples here:
https://clang.llvm.org/docs/DiagnosticsReference.html#wdocumentation

Reviewed By: yfeldblum

Differential Revision: D23872718

fbshipit-source-id: 0bb803c6e9412e72985c17415b424be08b51a693

folly/fibers/Baton.h

@@ -126,7 +126,7 @@ class Baton {
    * Puts active fiber to sleep. Returns when post is called or the deadline
    * expires.
    *
-   * @param timeout Baton will be automatically awaken if deadline expires
+   * @param deadline Baton will be automatically awaken if deadline expires
    *
    * @return true if was posted, false if timeout expired
    */
@@ -140,7 +140,7 @@ class Baton {
    * Puts active fiber to sleep. Returns when post is called or the deadline
    * expires.
    *
-   * @param timeout Baton will be automatically awaken if deadline expires
+   * @param deadline Baton will be automatically awaken if deadline expires
    * @param mainContextFunc this function is immediately executed on the main
    *        context.
    *
@@ -155,7 +155,7 @@ class Baton {
    * Puts active fiber to sleep. Returns when post is called or the deadline
    * expires.
    *
-   * @param timeout Baton will be automatically awaken if deadline expires
+   * @param deadline Baton will be automatically awaken if deadline expires
    * @param mainContextFunc this function is immediately executed on the main
    *        context.
    *

folly/fibers/FiberManagerInternal.h

@@ -164,7 +164,7 @@ class FiberManager : public ::folly::Executor {
   /**
    * Initializes, but doesn't start FiberManager loop
    *
-   * @param loopController
+   * @param loopController A LoopController object
    * @param options FiberManager options
    */
   explicit FiberManager(
@@ -174,7 +174,7 @@ class FiberManager : public ::folly::Executor {
   /**
    * Initializes, but doesn't start FiberManager loop
    *
-   * @param loopController
+   * @param loopController A LoopController object
    * @param options FiberManager options
    * @tparam LocalT only local of this type may be stored on fibers.
    *                Locals of other types will be considered thread-locals.
@@ -236,7 +236,7 @@ class FiberManager : public ::folly::Executor {
    * Sets exception callback which will be called if any of the tasks throws an
    * exception.
    *
-   * @param ec
+   * @param ec An ExceptionCallback object.
    */
   void setExceptionCallback(ExceptionCallback ec);
 

folly/fibers/Promise.h

@@ -51,7 +51,7 @@ class Promise {
   /**
    * Fulfill the promise with a given try
    *
-   * @param t
+   * @param t A Try with either a value or an error.
    */
   void setTry(folly::Try<T>&& t);
 

folly/io/async/EventBase.h

@@ -782,7 +782,7 @@ class EventBase : public TimeoutManager,
    * Setup execution observation/instrumentation for every EventHandler
    * executed in this EventBase.
    *
-   * @param executionObserver   EventHandle's execution observer.
+   * @param observer EventHandle's execution observer.
    */
   void setExecutionObserver(ExecutionObserver* observer) {
     executionObserver_ = observer;