INSTALL.md: Remove references to pandoc-citeproc.

Closes #6857.

INSTALL.md

@@ -49,10 +49,6 @@ Alternatively, you can install pandoc using
 
      brew install pandoc
 
-To include pandoc's citation parser:
-
-     brew install pandoc-citeproc
-
 Homebrew can also install other software that integrates with Pandoc.
 For example, to install [librsvg] (its `rsvg-convert` covers formats
 without SVG support), [Python] (to use Pandoc filters), and
@@ -86,9 +82,8 @@ not outdated. Pandoc is in the [Debian], [Ubuntu], [Slackware],
 To get the latest release, we provide a binary package for amd64
 architecture on the **[download page]**.
 
-This provides both `pandoc` and `pandoc-citeproc`.
-The executables are statically linked and
-have no dynamic dependencies or dependencies on external
+The executable is statically linked and
+has no dynamic dependencies or dependencies on external
 data files.  Note:  because of the static
 linking, the pandoc binary from this package cannot use lua
 filters that require external lua modules written in C.
@@ -98,8 +93,7 @@ Both a tarball and a deb installer are provided.  To install the deb:
     sudo dpkg -i $DEB
 
 where `$DEB` is the path to the downloaded deb.  This will
-install the `pandoc` and `pandoc-citeproc` executables and
-man pages.
+install the `pandoc` executable and man page.
 
 If you use an RPM-based distro, you may be able to install
 the deb from our download page using `alien`.
@@ -149,7 +143,7 @@ The official Docker images for pandoc can be found at
 [dockerhub](https://hub.docker.com/).
 
 The [pandoc/core](https://hub.docker.com/r/pandoc/core)
-image contains `pandoc` and `pandoc-citeproc`.
+image contains `pandoc`.
 
 The [pandoc/latex](https://hub.docker.com/r/pandoc/latex)
 image also contains the minimal LaTeX installation needed
@@ -246,26 +240,20 @@ The easiest way to build pandoc from source is to use [stack][stack]:
 
     [Not sure where `$CABALDIR` is?](http://www.haskell.org/haskellwiki/Cabal-Install#The_cabal-install_configuration_file)
 
-5.  If you want to process citations with pandoc, you will also need to
-    install a separate package, `pandoc-citeproc`.  This can be installed
-    using cabal:
-
-        cabal install pandoc-citeproc
-
-    By default `pandoc-citeproc` uses the "i;unicode-casemap" method
+5.  By default `pandoc` uses the "i;unicode-casemap" method
     to sort bibliography entries (RFC 5051).  If you would like to
     use the locale-sensitive unicode collation algorithm instead,
-    specify the `unicode_collation` flag:
+    specify the `icu` flag (which affects the dependency `citeproc`):
 
-        cabal install pandoc-citeproc -funicode_collation
+        cabal install pandoc -ficu
 
     Note that this requires the `text-icu` library, which in turn
     depends on the C library `icu4c`.  Installation directions
     vary by platform.  Here is how it might work on macOS with Homebrew:
 
         brew install icu4c
-        stack install pandoc-citeproc \
-          --flag "pandoc-citeproc:unicode_collation" \
+        stack install pandoc \
+          --flag "citeproc:icu" \
           --extra-lib-dirs=/usr/local/opt/icu4c/lib \
           --extra-include-dirs=/usr/local/opt/icu4c/include
 
@@ -274,8 +262,6 @@ The easiest way to build pandoc from source is to use [stack][stack]:
     accordingly. If `MANUAL.txt` has been modified, the man page can be
     rebuilt: `make man/pandoc.1`.
 
-    The `pandoc-citeproc.1` man page will also be installed automatically.
-
 
 ### Custom cabal method