Fix a few typos in sh.1

src/cmd/ksh93/sh.1

@@ -2270,7 +2270,7 @@ The value consists of blank separated
 .IB name = value\^
 words.  For each
 .I name\^
-that is the name of a know option the variable
+that is the name of a known option the variable
 .BI .sh.opt_ name\^
 is assigned
 .IR value .
@@ -4238,7 +4238,7 @@ by defining the first sub-variable name as
 and defining its type as the base type.
 Any remaining definitions will be additions and modifications
 that apply to the new type.
-If the new type name is the same is that of the base type,
+If the new type name is the same as that of the base type,
 the type will be replaced and the original type will
 no longer be accessible.
 .PP
@@ -4247,7 +4247,7 @@ The
 command with the
 .B \-T
 and no option argument or operands will write all the type definitions to
-standard output in a form that that can be read in to create all they types.
+standard output in a form that can be read in to create all the types.
 .SS Jobs.
 .PP
 If the
@@ -4483,7 +4483,7 @@ where
 .I path\^
 names an
 existing directory
-then that directory is searched after immediately after the current directory
+then that directory is searched immediately after the current directory
 as if it were found in the
 .B
 .SM FPATH