[TableGen] Improve a couple of descriptions in the command guide

Differential Revision: https://reviews.llvm.org/D91484

llvm/docs/CommandGuide/tblgen.rst

@@ -32,7 +32,11 @@ General Options
 
 .. option:: -help
 
- Print a summary of command line options.
+ Print a description of the command line options.
+
+.. option:: -help-list
+
+  Print a description of the command line options in a simple list format.
 
 .. option:: -D=macroname
 
@@ -79,12 +83,16 @@ General Options
 
 .. option:: -stats
 
-  Enable statistics output.
+  Print a report with any statistics collected by the backend.
 
 .. option:: -time-phases
 
   Time the parser and backend phases and print a report.
 
+.. option:: -version
+
+ Show the version number of the program.
+
 .. option:: -write-if-changed
 
   Write the output file only if it is new or has changed.
@@ -301,11 +309,6 @@ llvm-tblgen Options
 
  Print expanded sets for testing DAG exprs.
 
-.. option:: -version
-
- Show the version number of the program.
-
-
 clang-tblgen Options
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