Documentation fixes (#103)

* Clarify that extended basic blocks are abbreviated as EBB.

* Fix typo.

* Fix a typo.

* Fix typos.

* Use the same phrase to indicate scalar-only as other places in the doc.

* Mention that `band_imm` and friends are scalar-only.

And mention that they're equivalent to their respective
non-immediate-form counterparts.

lib/cretonne/meta/base/instructions.py

@@ -713,7 +713,8 @@ imul_imm = Instruction(
         'imul_imm', """
         Integer multiplication by immediate constant.
 
-        Polymorphic over all scalar integer types.
+        Polymorphic over all scalar integer types, but does not support vector
+        types.
         """,
         ins=(x, Y), outs=a)
 
@@ -912,18 +913,33 @@ a = Operand('a', iB)
 band_imm = Instruction(
         'band_imm', """
         Bitwise and with immediate.
+
+        Same as :inst:`band`, but one operand is an immediate constant.
+
+        Polymorphic over all scalar integer types, but does not support vector
+        types.
         """,
         ins=(x, Y), outs=a)
 
 bor_imm = Instruction(
         'bor_imm', """
         Bitwise or with immediate.
+
+        Same as :inst:`bor`, but one operand is an immediate constant.
+
+        Polymorphic over all scalar integer types, but does not support vector
+        types.
         """,
         ins=(x, Y), outs=a)
 
 bxor_imm = Instruction(
         'bxor_imm', """
         Bitwise xor with immediate.
+
+        Same as :inst:`bxor`, but one operand is an immediate constant.
+
+        Polymorphic over all scalar integer types, but does not support vector
+        types.
         """,
         ins=(x, Y), outs=a)