[llvm-objdump] Update the doc for --disassemble-functions.

Update the doc after llvm-svn: 364121 is landed.
With two more trivial fixes that are not related to
--disassemble-functions but still about llvm-objdump.

Reviewers: jhenderson, grimar, MaskRay, rupprecht, peter.smith

Reviewed by: jhenderson, MaskRay

Differential Revision: https://reviews.llvm.org/D63787

llvm-svn: 364573
diff --git a/llvm/docs/CommandGuide/llvm-objdump.rst b/llvm/docs/CommandGuide/llvm-objdump.rst
index 3ebd7fc..5e18872 100644
--- a/llvm/docs/CommandGuide/llvm-objdump.rst
+++ b/llvm/docs/CommandGuide/llvm-objdump.rst
@@ -35,9 +35,11 @@
   Display assembler mnemonics for the machine instructions. Disassembles all
   sections found in the input file(s) by default.
   
-.. option:: --disassemble-functions=<func1[,func2,...]>
+.. option:: --disassemble-functions=<symbol1[,symbol2,...]>
 
-  Disassemble only the specified symbols. Implies :option:`--disassemble`.
+  Disassemble only the specified symbols. Takes demangled symbol names when
+  :option:`--demangle` is specified, otherwise takes mangled symbol names.
+  Implies :option:`--disassemble`.
 
 .. option:: --dwarf=<value>
 
@@ -111,7 +113,7 @@
 
 .. option:: --arch-name=<string>
 
-  Specify the target architecture when disassembling. Use :option:``--version``
+  Specify the target architecture when disassembling. Use :option:`--version`
   for a list of available targets.
 
 .. option:: -C, --demangle
@@ -193,7 +195,7 @@
 
 .. option:: --x86-asm-syntax=<style>
 
-  When used with the ``--disassemble`` option, choose style of code to emit from
+  When used with :option:`--disassemble`, choose style of code to emit from
   X86 backend. Supported values are:
 
    .. option:: att