help: add FAQ to help topics

- Initial question "what does 'In file [heap]' mean?"
 - Also updated README with some quick-install tips for RPM based systems.

README

@@ -22,3 +22,23 @@ Debugging symbols
 - The programs and libraries you want to profile should be compiled
   with -fno-omit-frame-pointer and have debugging symbols available,
   or you won't get much usable information.
+
+
+Building Sysprof
+----------------
+
+You need some packages installed. The package names may vary depending on your
+distribution, the following command works on Fedora 25:
+
+    sudo dnf install gcc make autoconf automake autopoint libtool ghc-gio
+
+Then do the following:
+
+    ./autogen.sh   # configure, generate makefiles etc.
+    make           # Build the code
+    make install   # Install (default prefix /usr/local)
+
+WARNING: `make install` will mostly install under the configured install prefix
+but installs systemd service configuration directly in the system default
+location `/usr/lib/systemd` so it won't work without root privileges, even if
+the install prefix is a user-owned directory.

help/C/faq.page

@@ -0,0 +1,46 @@
+<page xmlns="http://projectmallard.org/1.0/"
+      xmlns:its="http://www.w3.org/2005/11/its"
+      type="topic"
+      id="faq">
+
+  <section id="what-does-heap-mean">
+    <info>
+      <link type="guide" xref="index#faq"/>
+    </info>
+    <title>What does "In file [heap]" mean?</title>
+
+    <p>This means that sysprof believes a function was called from somewhere in
+    the program's heap (where <code>malloc</code> allocates memory) rather than
+    the code section (where executable code normally lives.) There are several
+    possible explanations.
+    </p>
+
+    <section>
+      <title>JIT (Just in Time) compilers</title>
+
+      <p>Languages like Java can generate executable code while a program is
+      running and store it in the heap. Sysprof is accurately reporting the
+      situation in this case.</p>
+    </section>
+
+    <section>
+      <title>Optimizing compilers</title>
+
+      <p>C and C++ compilers can optimize away information needed to determine a
+      function's caller, so it is mistaken for [heap]. You can still tell how
+      often each function is called by the program, but not always from
+      where.</p>
+
+      <note>
+        <p>For gcc, the flag <code>-fno-omit-frame-pointer</code> will prevent
+        this optimization. The flag is not always needed, for example on x86_64
+        machines it is only needed with -O3 optimization.</p>
+      </note>
+
+      <note>
+        <p>To get the most detailed and accurate call tree from un-optimized
+        code, use these flags: <code>-ggdb -fno-omit-frame-pointer -O0</code></p>
+      </note>
+    </section>
+  </section>
+</page>

help/C/index.page

@@ -15,4 +15,8 @@
     <title>Profiling</title>
   </section>
 
+  <section id="faq">
+    <title>Frequently Asked Questions</title>
+  </section>
+
 </page>

help/Makefile.am

@@ -10,6 +10,7 @@ HELP_FILES = \
 	index.page \
 	introduction.page \
 	profiling.page \
+	faq.page \
 	legal.xml
 
 # Translated languages