Fixed many typos

doc/coding.sgml

@@ -59,7 +59,7 @@ slower than the same code for unsigned types.
 
 <sect>Use chars instead of ints if possible<p>
 
-While in arithmetic operations, chars are immidiately promoted to ints, they
+While in arithmetic operations, chars are immediately promoted to ints, they
 are passed as chars in parameter lists and are accessed as chars in variables.
 The code generated is usually not much smaller, but it is faster, since
 accessing chars is faster. For several operations, the generated code may be