Documented the newly created functions in stdlib_string_type.md

Author: aman-godara

doc/specs/stdlib_string_type.md

@@ -1041,6 +1041,185 @@ end program demo
 ```
 
 
+<!-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
+### To\_lower function
+
+#### Description
+
+Returns a new string_type instance which holds the lowercase version of the character sequence hold by the input string.
+
+#### Syntax
+
+`lowercase_string = [[stdlib_string_type(module): to_lower(interface)]] (string)`
+
+#### Status
+
+Experimental
+
+#### Class
+
+Elemental function.
+
+#### Argument
+
+`string`: Instance of `string_type`. This argument is `intent(in)`.
+
+#### Result Value
+
+The Result is a scalar `string_type` value.
+
+#### Example
+
+```fortran
+program demo
+  use stdlib_string_type
+  implicit none
+  type(string_type) :: string, lowercase_string
+
+  string = "Lowercase This String"
+  ! string <-- "Lowercase This String"
+
+  lowercase_string = to_lower(string)
+  ! string <-- "Lowercase This String"
+  ! lowercase_string <-- "lowercase this string"
+end program demo
+```
+
+
+<!-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
+### To\_upper function
+
+#### Description
+
+Returns a new string_type instance which holds the uppercase version of the character sequence hold by the input string.
+
+#### Syntax
+
+`uppercase_string = [[stdlib_string_type(module): to_upper(interface)]] (string)`
+
+#### Status
+
+Experimental
+
+#### Class
+
+Elemental function.
+
+#### Argument
+
+`string`: Instance of `string_type`. This argument is `intent(in)`.
+
+#### Result Value
+
+The Result is a scalar `string_type` value.
+
+#### Example
+
+```fortran
+program demo
+  use stdlib_string_type
+  implicit none
+  type(string_type) :: string, uppercase_string
+
+  string = "Uppercase This String"
+  ! string <-- "Uppercase This String"
+
+  uppercase_string = to_upper(string)
+  ! string <-- "Uppercase This String"
+  ! uppercase_string <-- "UPPERCASE THIS STRING"
+end program demo
+```
+
+
+<!-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
+### To\_title function
+
+#### Description
+
+Returns a new string_type instance which holds the titlecase version of the character sequence hold by the input string.
+
+#### Syntax
+
+`titlecase_string = [[stdlib_string_type(module): to_title(interface)]] (string)`
+
+#### Status
+
+Experimental
+
+#### Class
+
+Elemental function.
+
+#### Argument
+
+`string`: Instance of `string_type`. This argument is `intent(in)`.
+
+#### Result Value
+
+The Result is a scalar `string_type` value.
+
+#### Example
+
+```fortran
+program demo
+  use stdlib_string_type
+  implicit none
+  type(string_type) :: string, titlecase_string
+
+  string = "Titlecase This String"
+  ! string <-- "Titlecase This String"
+
+  titlecase_string = to_title(string)
+  ! string <-- "Titlecase This String"
+  ! titlecase_string <-- "Titlecase this string"
+end program demo
+```
+
+<!-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
+### Reverse function
+
+#### Description
+
+Returns a new string_type instance which holds the reversed version of the character sequence hold by the input string.
+
+#### Syntax
+
+`reverse_string = [[stdlib_string_type(module): reverse(interface)]] (string)`
+
+#### Status
+
+Experimental
+
+#### Class
+
+Elemental function.
+
+#### Argument
+
+`string`: Instance of `string_type`. This argument is `intent(in)`.
+
+#### Result Value
+
+The Result is a scalar `string_type` value.
+
+#### Example
+
+```fortran
+program demo
+  use stdlib_string_type
+  implicit none
+  type(string_type) :: string, reverse_string
+  
+  string = "Reverse This String"
+  ! string <-- "Reverse This String"
+
+  reverse_string = reverse(string)
+  ! string <-- "Reverse This String"
+  ! reverse_string <-- "gnirtS sihT esreveR"
+end program demo
+```
+
+
 <!-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
 ### Comparison operator greater
 

src/stdlib_string_type.f90

@@ -93,34 +93,34 @@ module stdlib_string_type
         module procedure :: repeat_string
     end interface repeat
 
-    !> Convert the character sequence hold by the input string to lower case
+    !> Returns the lowercase version of the character sequence hold by the input string
     !>
-    !> This method is Elemental and returns a new string_type instance which holds lowercase
-    !> version of the character sequence hold by the input string
+    !> This method is Elemental and returns a new string_type instance which holds this
+    !> lowercase character sequence
     interface to_lower
         module procedure :: to_lower_string
     end interface to_lower
 
-    !> Convert the character sequence hold by the input string to upper case
+    !> Returns the uppercase version of the character sequence hold by the input string
     !>
-    !> This method is Elemental and returns a new string_type instance which holds uppercase
-    !> version of the character sequence hold by the input string
+    !> This method is Elemental and returns a new string_type instance which holds this
+    !> uppercase character sequence
     interface to_upper
         module procedure :: to_upper_string
     end interface to_upper
 
-    !> Convert the character sequence hold by the input string to title case
+    !> Returns the titlecase version of the character sequence hold by the input string
     !>
-    !> This method is Elemental and returns a new string_type instance which holds titlecase
-    !> version of the character sequence hold by the input string
+    !> This method is Elemental and returns a new string_type instance which holds this
+    !> titlecase character sequence
     interface to_title
         module procedure :: to_title_string
     end interface to_title
 
-    !> Reverse the character sequence hold by the input string
+    !> Reverses the character sequence hold by the input string
     !> 
-    !> This method is Elemental and returns a new string_type instance which holds reversed
-    !> sequence of the character sequence hold by the input string
+    !> This method is Elemental and returns a new string_type instance which holds this
+    !> reverse character sequence
     interface reverse
         module procedure :: reverse_string
     end interface reverse