added dependency of modules in Makefile.manual, updated comments, fixed typo in README.md

Author: aman-godara

README.md

@@ -138,7 +138,7 @@ To test your build, run the test suite after the build has finished with
 cmake --build build --target test
 ```
 
-Please report failing tests on our [issue tracker](https://github.com/fortran-lang/stdlib/issues/new/choose) including details on the compiler used, the operating system and platform architecture.
+Please report failing tests on our [issue tracker](https://github.com/fortran-lang/stdlib/issues/new/choose) including details of the compiler used, the operating system and platform architecture.
 
 To install the project to the declared prefix run
 

src/Makefile.manual

@@ -109,3 +109,4 @@ stdlib_stats_var.o: \
 stdlib_stats_distribution_PRNG.o: \
         stdlib_kinds.o \
 	stdlib_error.o
+stdlib_string_type.o: stdlib_ascii.o

src/stdlib_string_type.f90

@@ -95,28 +95,32 @@ module stdlib_string_type
 
     !> Convert the character sequence hold by the input string to lower case
     !>
-    !> Elemental or pure ???? Does not return anything
+    !> This method is Elemental and returns a new string_type instance which holds lowercase
+    !> version of the character sequence hold by the input string
     interface to_lower
         module procedure :: to_lower_string
     end interface to_lower
 
     !> Convert the character sequence hold by the input string to upper case
     !>
-    !> Elemental or pure ???? Does not return anything
+    !> This method is Elemental and returns a new string_type instance which holds uppercase
+    !> version of the character sequence hold by the input string
     interface to_upper
         module procedure :: to_upper_string
     end interface to_upper
 
     !> Convert the character sequence hold by the input string to title case
     !>
-    !> Elemental or pure ???? Does not return anything
+    !> This method is Elemental and returns a new string_type instance which holds titlecase
+    !> version of the character sequence hold by the input string
     interface to_title
         module procedure :: to_title_string
     end interface to_title
 
     !> Reverse the character sequence hold by the input string
     !> 
-    !> Elemental or pure ???? Does not return anything
+    !> This method is Elemental and returns a new string_type instance which holds reversed
+    !> sequence of the character sequence hold by the input string
     interface reverse
         module procedure :: reverse_string
     end interface reverse