added tab completion to REPL docs

doc/manual/interacting-with-julia.rst

@@ -161,3 +161,20 @@ The Julia REPL makes great use of key bindings. Several control-key bindings we
 +------------------------+----------------------------------------------------+
 | Delete, ``^D`` | Forward delete one character (when buffer has text)|
 +------------------------+----------------------------------------------------+
+
+Tab completion
+--------------
+
+In both the Julian and help modes of the REPL, one can enter the first few characters of a function or type and then press the tab key to get a list all matches::
+
+ julia> stri
+ stride strides string stringmime strip
+
+ julia> Stri
+ StridedArray StridedVecOrMat String
+ StridedMatrix StridedVector
+
+The tab key is also used to substitute LaTeX math symbols with their unicode equivalents::
+
+ julia> \alpha[TAB]
+ julia> α