[docs] Discuss manpage output.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176199 91177308-0d34-0410-b5e6-96231b3b80d8

docs/README.txt

@@ -4,9 +4,9 @@ LLVM Documentation
 LLVM's documentation is written in reStructuredText, a lightweight
 plaintext markup language (file extension `.rst`). While the
 reStructuredText documentation should be quite readable in source form, it
-is meant to be processed by the Sphinx documentation generation system to
-create HTML pages which are hosted on <http://llvm.org/docs/> and updated
-after every commit.
+is mostly meant to be processed by the Sphinx documentation generation
+system to create HTML pages which are hosted on <http://llvm.org/docs/> and
+updated after every commit. Manpage output is also supported, see below.
 
 If you instead would like to generate and view the HTML locally, install
 Sphinx <http://sphinx-doc.org/> and then do:
@@ -22,3 +22,21 @@ If you are interested in writing new documentation, you will want to read
 `SphinxQuickstartTemplate.rst` which will get you writing documentation
 very fast and includes examples of the most important reStructuredText
 markup syntax.
+
+Manpage Output
+===============
+
+Building the manpages is similar to building the HTML documentation. The
+primary difference is to use the `man` makefile target, instead of the
+default (which is `html`). Sphinx then produces the man pages in the
+directory `_build/man/`.
+
+    cd docs/
+    make -f Makefile.sphinx man
+    man -l _build/man/FileCheck.1
+
+The correspondence between .rst files and man pages is
+`docs/CommandGuide/Foo.rst` <-> `_build/man/Foo.1`.
+These .rst files are also included during HTML generation so they are also
+viewable online (as noted above) at e.g.
+`http://llvm.org/docs/CommandGuide/Foo.html`.