Small changes re build requirements + sophia limitations

doc/sphinx/book/box/limitations.rst

@@ -39,8 +39,7 @@ Length of an index name or space name or user name
     32 (``box.schema.NAME_MAX``).
 
 Limitations which are only applicable for the sophia storage engine
-    The maximum number of fields in an index is always 1, that is, multi-part
-    indexes are not supported. The maximum number of indexes in a space is
+    The maximum number of indexes in a space is
     always 1, that is, secondary indexes are not supported. Indexes must be
     type=TREE, that is, the options type=HASH or type=RTREE or type=BITSET are
     not supported. Indexes must be unique, that is, the option unique=false

doc/sphinx/dev_guide/building_from_source.rst

@@ -25,8 +25,9 @@ explain what the steps are, then on the Internet you can look at some example sc
    Here are names of tools and libraries which may have to be installed in advance,
    using ``sudo apt-get`` (for Ubuntu), ``sudo yum install`` (for CentOS), or the
    equivalent on other platforms. Different platforms may use slightly different
-   names. Do not worry about the ones marked `optional, only in Mac OS scripts`
-   unless your platform is Mac OS.
+   names. Ignore the ones marked `optional, only in Mac OS scripts`
+   unless the platform is Mac OS. Ignore the one marked `optional,
+   only for documentation` unless the intent is to use the ``-DENABLE_DOC`` option in step 5.
 
    * **gcc and g++, or clang**                # see above
    * **git**                                  # see above
@@ -34,6 +35,7 @@ explain what the steps are, then on the Internet you can look at some example sc
    * **libreadline-dev or libreadline6-dev or readline-devel**  # for interactive mode
    * **autoconf**                             # optional, only in Mac OS scripts
    * **zlib1g** or **zlib**                   # optional, only in Mac OS scripts
+   * **doxygen**                              # optional, only for documentation
 
 2. Set up python modules for running the test suite or creating documentation.
    This step is optional. Python modules are not necessary for building Tarantool
@@ -108,6 +110,7 @@ explain what the steps are, then on the Internet you can look at some example sc
      pip install tarantool\>0.4 --user
      # For documentation
      sudo pip install pelican
+     sudo pip install breathe
      sudo pip install -U sphinx
 
 3. Use :code:`git` to download the latest source code from the