A bunch of typo fixes.

Fixes PR11131.

collects/rackunit/scribblings/check.scrbl

@@ -111,7 +111,8 @@ fails.  A common error is to use an expression instead of a
 function of no arguments for @racket[thunk].  Remember that
 checks are conceptually functions.}
 
-Here are two example, one showing a test that succeeds, and one showing a common error:
+Here are two examples, one showing a test that succeeds, and one showing
+a common error:
 
 @racketblock[
   (check-exn exn:fail? 
@@ -129,7 +130,7 @@ Checks that @racket[thunk] does not raise any exceptions.
 The optional @racket[message] is included in the output if
 the check fails.}
 
-@defproc[(fail (message string? "")) #t]{This checks fails unconditionally.  Good for creating test stubs that youintend to fill out later.  The optional @racket[message] is included in the output if the check fails.}
+@defproc[(fail (message string? "")) #t]{This checks fails unconditionally.  Good for creating test stubs that you intend to fill out later.  The optional @racket[message] is included in the output if the check fails.}
 
 
 @defproc[(check-regexp-match (regexp regexp?) (string string?)) #t]{Checks that @racket[regexp] matches the @racket[string].}
@@ -146,7 +147,7 @@ This check will fail:
 
 @section{Augmenting Information on Check Failure}
 
-When an check fails it stores information including the name
+When a check fails it stores information including the name
 of the check, the location and message (if available), the
 expression the check is called with, and the parameters to
 the check.  Additional information can be stored by using
@@ -156,7 +157,7 @@ the @racket[with-check-info*] function, and the
 @defstruct[check-info ([name symbol?] [value any])]{
 
 A check-info structure stores information associated
-with the context of execution of an check.}
+with the context of execution of a check.}
 
 The are several predefined functions that create check
 information structures with predefined names.  This avoids
@@ -231,7 +232,7 @@ Firstly, a check should be considered a function, even
 though most uses are actually macros.  In particular, checks
 always evaluate their arguments exactly once before
 executing any expressions in the body of the checks.  Hence
-if you wish to write checks that evalute user defined code
+if you wish to write checks that evaluate user defined code
 that code must be wrapped in a thunk (a function of no
 arguments) by the user.  The predefined @racket[check-exn]
 is an example of this type of check.

collects/rackunit/scribblings/philosophy.scrbl

@@ -5,7 +5,7 @@
 
 RackUnit is designed to allow tests to evolve in step with
 the evolution of the program under testing.  RackUnit
-scales from the unstructed checks suitable for simple
+scales from the unstructured checks suitable for simple
 programs to the complex structure necessary for large
 projects.
 
@@ -83,7 +83,7 @@ RackUnit manner (for example, test results may be logged
 for the purpose of improving software quality, or they may
 be displayed on a website to indicate service quality). For
 these programmers it is necessary to delay the execution of
-tests so they can processed in the programmer's chosen
+tests so they can be processed in the programmer's chosen
 manner. To do this, the programmer simply wraps a test-suite
 around their tests:
 

collects/rackunit/scribblings/quick-start.scrbl

@@ -119,7 +119,7 @@ we're testing.  We can give a test case a name with the
     lst)))
 ]
 
-Now if we want to structure our tests are bit more we can
+Now if we want to structure our tests a bit more we can
 group them into a test suite:
 
 @racketblock[

collects/scribblings/reference/collects.scrbl

@@ -59,7 +59,7 @@ The translation of a @racket[planet] or @racket[lib] path to a
 resolver}, as specified by the @racket[current-module-name-resolver]
 parameter.
 
-For the default @tech{module name resolver}, The search path for
+For the default @tech{module name resolver}, the search path for
 collections is determined by the
 @racket[current-library-collection-paths] parameter. The list of paths
 in @racket[current-library-collection-paths] is searched from first to

collects/scribblings/reference/sequences.scrbl

@@ -60,7 +60,7 @@ sequence types, each extraction implies a side effect; for example,
 extracting the sequence of bytes from a port cause the bytes to be
 read from the port.
 
-Inidvidual elements of a sequence typically correspond to single
+Individual elements of a sequence typically correspond to single
 values, but an element may also correspond to multiple values. For
 example, a hash table generates two values---a key and its value---for
 each element in the sequence.