Add section about Boost version requirement

INSTALL.md

@@ -13,7 +13,8 @@ $ make install
 ## Important Installation Notes
 
 1. GTSAM requires the following libraries to be installed on your system:
-    - BOOST version 1.65 or greater (install through Linux repositories or MacPorts)
+    - BOOST version 1.65 or greater (install through Linux repositories or MacPorts). Please see [Boost Notes](#boost-notes).
+
     - Cmake version 3.0 or higher
     - Support for XCode 4.3 command line tools on Mac requires CMake 2.8.8 or higher
 
@@ -66,11 +67,15 @@ execute commands as follows for an out-of-source build:
   This will build the library and unit tests, run all of the unit tests,
   and then install the library itself.
 
+## Boost Notes
+
+Versions of Boost prior to 1.65 have a known bug that prevents proper "deep" serialization of objects, which means that objects encapsulated inside other objects don't get serialized.
+This is particularly seen when using `clang` as the C++ compiler.
+
+For this reason we require Boost>=1.65, and recommend installing it through alternative channels when it is not available through your operating system's primary package manager.
+
 ## Known Issues
 
-- When using `GTSAM_BUILD_WITH_MARCH_NATIVE=ON`, you may encounter issues in running tests which we are still investigating:
-  - Use of a version of GCC < 7.5 results in an "Indeterminant Linear System" error for `testSmartProjectionFactor`.
-  - Use of Boost version < 1.65 with clang will give a segfault for mulitple test cases.
 - MSVC 2013 is not yet supported because it cannot build the serialization module of Boost 1.55 (or earlier).
 
 # Windows Installation