[DOC] Fix outdated results in examples

Some example results in the docs no longer match what Ruby prints:

* Array#flatten and Array#flatten!: Set#inspect now shows Set[6, 7]
* Module: Mod.constants also includes Math::DomainError
* Module#const_get and Module#const_set: Floats are shown with full
  precision
* Complex#imag: sin(PI/4) is 0.7071067811865475
* String#<<: missing # in #<Encoding:UTF-8>
* Enumerable#inject: typo #=>>

array.c

@@ -6851,16 +6851,16 @@ single_nested_array(VALUE ary)
  *  With non-negative integer argument +depth+, flattens recursively through +depth+ levels:
  *
  *    a = [ 0, [ 1, [2, 3], 4 ], 5, {foo: 0}, Set.new([6, 7]) ]
- *    a                   # => [0, [1, [2, 3], 4], 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.dup.flatten!(1)   # => [0, 1, [2, 3], 4, 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.dup.flatten!(1.1) # => [0, 1, [2, 3], 4, 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.dup.flatten!(2)   # => [0, 1, 2, 3, 4, 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.dup.flatten!(3)   # => [0, 1, 2, 3, 4, 5, {foo: 0}, #<Set: {6, 7}>]
+ *    a                   # => [0, [1, [2, 3], 4], 5, {foo: 0}, Set[6, 7]]
+ *    a.dup.flatten!(1)   # => [0, 1, [2, 3], 4, 5, {foo: 0}, Set[6, 7]]
+ *    a.dup.flatten!(1.1) # => [0, 1, [2, 3], 4, 5, {foo: 0}, Set[6, 7]]
+ *    a.dup.flatten!(2)   # => [0, 1, 2, 3, 4, 5, {foo: 0}, Set[6, 7]]
+ *    a.dup.flatten!(3)   # => [0, 1, 2, 3, 4, 5, {foo: 0}, Set[6, 7]]
  *
  *  With +nil+ or negative argument +depth+, flattens all levels:
  *
- *    a.dup.flatten!     # => [0, 1, 2, 3, 4, 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.dup.flatten!(-1) # => [0, 1, 2, 3, 4, 5, {foo: 0}, #<Set: {6, 7}>]
+ *    a.dup.flatten!     # => [0, 1, 2, 3, 4, 5, {foo: 0}, Set[6, 7]]
+ *    a.dup.flatten!(-1) # => [0, 1, 2, 3, 4, 5, {foo: 0}, Set[6, 7]]
  *
  *  Related: Array#flatten;
  *  see also {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
@@ -6920,17 +6920,17 @@ rb_ary_flatten_bang(int argc, VALUE *argv, VALUE ary)
  *  With non-negative integer argument +depth+, flattens recursively through +depth+ levels:
  *
  *    a = [ 0, [ 1, [2, 3], 4 ], 5, {foo: 0}, Set.new([6, 7]) ]
- *    a              # => [0, [1, [2, 3], 4], 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.flatten(0)   # => [0, [1, [2, 3], 4], 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.flatten(1  ) # => [0, 1, [2, 3], 4, 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.flatten(1.1) # => [0, 1, [2, 3], 4, 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.flatten(2)   # => [0, 1, 2, 3, 4, 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.flatten(3)   # => [0, 1, 2, 3, 4, 5, {foo: 0}, #<Set: {6, 7}>]
+ *    a              # => [0, [1, [2, 3], 4], 5, {foo: 0}, Set[6, 7]]
+ *    a.flatten(0)   # => [0, [1, [2, 3], 4], 5, {foo: 0}, Set[6, 7]]
+ *    a.flatten(1  ) # => [0, 1, [2, 3], 4, 5, {foo: 0}, Set[6, 7]]
+ *    a.flatten(1.1) # => [0, 1, [2, 3], 4, 5, {foo: 0}, Set[6, 7]]
+ *    a.flatten(2)   # => [0, 1, 2, 3, 4, 5, {foo: 0}, Set[6, 7]]
+ *    a.flatten(3)   # => [0, 1, 2, 3, 4, 5, {foo: 0}, Set[6, 7]]
  *
  *  With +nil+ or negative +depth+, flattens all levels.
  *
- *    a.flatten     # => [0, 1, 2, 3, 4, 5, {foo: 0}, #<Set: {6, 7}>]
- *    a.flatten(-1) # => [0, 1, 2, 3, 4, 5, {foo: 0}, #<Set: {6, 7}>]
+ *    a.flatten     # => [0, 1, 2, 3, 4, 5, {foo: 0}, Set[6, 7]]
+ *    a.flatten(-1) # => [0, 1, 2, 3, 4, 5, {foo: 0}, Set[6, 7]]
  *
  *  Related: Array#flatten!;
  *  see also {Methods for Converting}[rdoc-ref:Array@Methods+for+Converting].

complex.c

@@ -762,7 +762,7 @@ rb_complex_real(VALUE self)
  * {polar coordinates}[rdoc-ref:Complex@Polar+Coordinates], the returned value
  * is computed, and may be inexact:
  *
- *   Complex.polar(1, Math::PI/4).imag # => 0.7071067811865476 # Square root of 2.
+ *   Complex.polar(1, Math::PI/4).imag # => 0.7071067811865475
  *
  */
 VALUE

enum.c

@@ -1021,7 +1021,7 @@ ary_inject_op(VALUE ary, VALUE init, VALUE op)
  *      end
  *
  *      position = "nnneesw".chars.reduce(Turtle.new, :move)
- *      position  #=>> #<Turtle:0x00000001052f4698 @y=2, @x=1>
+ *      position  #=> #<Turtle:0x00000001052f4698 @y=2, @x=1>
  *
  *  <b>Third Shortcut: Reducer With no Initial Value</b>
  *

object.c

@@ -1797,7 +1797,7 @@ rb_obj_cmp(VALUE obj1, VALUE obj2)
  *       end
  *     end
  *     Mod.class              #=> Module
- *     Mod.constants          #=> [:CONST, :PI, :E]
+ *     Mod.constants          #=> [:CONST, :DomainError, :PI, :E]
  *     Mod.instance_methods   #=> [:meth]
  *
  */
@@ -2611,7 +2611,7 @@ rb_mod_attr_accessor(int argc, VALUE *argv, VALUE klass)
  *  The value of the constant is returned if a definition is found,
  *  otherwise a +NameError+ is raised.
  *
- *     Math.const_get(:PI)   #=> 3.14159265358979
+ *     Math.const_get(:PI)   #=> 3.141592653589793
  *
  *  This method will recursively look up constant names if a namespaced
  *  class name is provided.  For example:
@@ -2751,8 +2751,8 @@ rb_mod_const_get(int argc, VALUE *argv, VALUE mod)
  *  Creates a new constant if no constant with the given name previously
  *  existed.
  *
- *     Math.const_set("HIGH_SCHOOL_PI", 22.0/7.0)   #=> 3.14285714285714
- *     Math::HIGH_SCHOOL_PI - Math::PI              #=> 0.00126448926734968
+ *     Math.const_set("HIGH_SCHOOL_PI", 22.0/7.0)   #=> 3.142857142857143
+ *     Math::HIGH_SCHOOL_PI - Math::PI              #=> 0.0012644892673496777
  *
  *  If +sym+ or +str+ is not a valid constant name a +NameError+ will be
  *  raised with a warning "wrong constant name".

string.c

@@ -4149,7 +4149,7 @@ rb_str_append_as_bytes(int argc, VALUE *argv, VALUE str)
  *  Raises RangeError if that codepoint is not representable in the encoding of +self+:
  *
  *    s = 'foo'
- *    s.encoding              # => <Encoding:UTF-8>
+ *    s.encoding              # => #<Encoding:UTF-8>
  *    s << 0x00110000         # 1114112 out of char range (RangeError)
  *    s = 'foo'.encode(Encoding::EUC_JP)
  *    s << 0x00800080         # invalid codepoint 0x800080 in EUC-JP (RangeError)