Added more comments

Added comments about M3/M4 cpu and alignment requirements.

linker.ld

@@ -1,6 +1,8 @@
 /*
  * Filename: linker.ld
  * Micro-Controller: stm32f103c8t6
+ * Cortex-M3 and Cortex-M4 only need to be 4byte aligned where as
+ * other's might need 8byte or something differnt.
  */
 
 
@@ -66,29 +68,30 @@ SECTIONS
     } > RAM AT > FLASH
 
     /* BSS: Placed in SRAM memory types. */
+    /* Holds all uninitialized globals and static variables.*/ 
     .bss :
     {
-        _sbss = .;                  /* */
-        *(.bss)                     /**/
-        *(COMMON)                   /**/
-        _ebss = .;                  /**/
+        _sbss = .;                  /* Start of BSS */
+        *(.bss)                     /* Uninitialized data */
+        *(COMMON)                   /* Common symbols (zero-init) */
+        _ebss = .;                  /* End of BSS */
     } > RAM
 
-    /* Stack Section: */
+    /* Stack Section: Sizes known at compile time. */
     ._stack :
     {
-        . = ALIGN(8);               /**/
-        _estack = .;                /**/
-        . = . + 2048;               /**/
-        _sstack = .;                /**/
+        . = ALIGN(8);               /* Align to 8-byte boundry */
+        _estack = .;                /* End of stack (top of the stack) */
+        . = . + 2048;               /* Reserve 2KB for stack */
+        _sstack = .;                /*Start of stack */
     } > RAM
 
-    /* Heap Section: */
+    /* Heap Section: Used for dynamic memory allocation. */
     .heap :
     {
-        _sheap = .;                 /**/
-        . = . + 2048;               /**/
-        _eheap = .;                 /**/
+        _sheap = .;                 /* Start of heap */
+        . = . + 2048;               /* Reserve 2 KB for heap */
+        _eheap = .;                 /* End of heap */
     } > RAM
 }