In docs, clarified when 'msg' describes the assertion. Also clarified…

… 'expected' in throws().

readme.markdown

@@ -190,13 +190,13 @@ Generate an assertion that will be skipped over.
 
 ## t.ok(value, msg)
 
-Assert that `value` is truthy with an optional description message `msg`.
+Assert that `value` is truthy with an optional description of the assertion `msg`.
 
 Aliases: `t.true()`, `t.assert()`
 
 ## t.notOk(value, msg)
 
-Assert that `value` is falsy with an optional description message `msg`.
+Assert that `value` is falsy with an optional description of the assertion `msg`.
 
 Aliases: `t.false()`, `t.notok()`
 
@@ -209,14 +209,14 @@ Aliases: `t.ifError()`, `t.ifErr()`, `t.iferror()`
 
 ## t.equal(actual, expected, msg)
 
-Assert that `actual === expected` with an optional description `msg`.
+Assert that `actual === expected` with an optional description of the assertion `msg`.
 
 Aliases: `t.equals()`, `t.isEqual()`, `t.is()`, `t.strictEqual()`,
 `t.strictEquals()`
 
 ## t.notEqual(actual, expected, msg)
 
-Assert that `actual !== expected` with an optional description `msg`.
+Assert that `actual !== expected` with an optional description of the assertion `msg`.
 
 Aliases: `t.notEquals()`, `t.notStrictEqual()`, `t.notStrictEquals()`,
 `t.isNotEqual()`, `t.isNot()`, `t.not()`, `t.doesNotEqual()`, `t.isInequal()`
@@ -225,17 +225,15 @@ Aliases: `t.notEquals()`, `t.notStrictEqual()`, `t.notStrictEquals()`,
 
 Assert that `actual` and `expected` have the same structure and nested values using
 [node's deepEqual() algorithm](https://github.com/substack/node-deep-equal)
-with strict comparisons (`===`) on leaf nodes and an optional description
-`msg`.
+with strict comparisons (`===`) on leaf nodes and an optional description of the assertion `msg`.
 
 Aliases: `t.deepEquals()`, `t.isEquivalent()`, `t.same()`
 
 ## t.notDeepEqual(actual, expected, msg)
 
 Assert that `actual` and `expected` do not have the same structure and nested values using
 [node's deepEqual() algorithm](https://github.com/substack/node-deep-equal)
-with strict comparisons (`===`) on leaf nodes and an optional description
-`msg`.
+with strict comparisons (`===`) on leaf nodes and an optional description of the assertion `msg`.
 
 Aliases: `t.notEquivalent()`, `t.notDeeply()`, `t.notSame()`,
 `t.isNotDeepEqual()`, `t.isNotDeeply()`, `t.isNotEquivalent()`,
@@ -245,25 +243,25 @@ Aliases: `t.notEquivalent()`, `t.notDeeply()`, `t.notSame()`,
 
 Assert that `actual` and `expected` have the same structure and nested values using
 [node's deepEqual() algorithm](https://github.com/substack/node-deep-equal)
-with loose comparisons (`==`) on leaf nodes and an optional description `msg`.
+with loose comparisons (`==`) on leaf nodes and an optional description of the assertion `msg`.
 
 Aliases: `t.looseEqual()`, `t.looseEquals()`
 
 ## t.notDeepLooseEqual(actual, expected, msg)
 
 Assert that `actual` and `expected` do not have the same structure and nested values using
 [node's deepEqual() algorithm](https://github.com/substack/node-deep-equal)
-with loose comparisons (`==`) on leaf nodes and an optional description `msg`.
+with loose comparisons (`==`) on leaf nodes and an optional description of the assertion `msg`.
 
 Aliases: `t.notLooseEqual()`, `t.notLooseEquals()`
 
 ## t.throws(fn, expected, msg)
 
-Assert that the function call `fn()` throws an exception. `expected`, if present, must be a `RegExp` or `Function`.
+Assert that the function call `fn()` throws an exception. `expected`, if present, must be a `RegExp` or `Function`. The `RegExp` matches the string representation of the exception, as generated by `err.toString()`. The `Function` is the exception thrown (e.g. `Error`). `msg` is an optional description of the assertion.
 
 ## t.doesNotThrow(fn, expected, msg)
 
-Assert that the function call `fn()` does not throw an exception.
+Assert that the function call `fn()` does not throw an exception. `msg` is an optional description of the assertion.
 
 ## t.test(name, [opts], cb)