added specs link in the description comments

Co-authored-by: Sebastian Ehlert <[email protected]>

Author: aman-godara

src/stdlib_strings.f90

@@ -94,7 +94,7 @@ module stdlib_strings
     end interface replace_all
 
     !> Left pad the input string
-    !> [Specifications](link to the specs - to be completed)
+    !> [Specifications](../page/specs/stdlib_strings.html#padl)
     !> Version: experimental
     interface padl
         module procedure :: padl_string_default
@@ -104,7 +104,7 @@ module stdlib_strings
     end interface padl
 
     !> Right pad the input string
-    !> [Specifications](link to the specs - to be completed)
+    !> [Specifications](../page/specs/stdlib_strings.html#padr)
     !> Version: experimental
     interface padr
         module procedure :: padr_string_default