Add installation instruction for nofib

If we run make boot without installing html and regex-compat we run into the following error:

[3 of 4] Compiling Slurp            ( Slurp.hs, Slurp.o )
 
Slurp.hs:13:1: error:
    Could not find module ‘Text.Regex’
    Perhaps you meant Text.Read (from base-4.11.0.0)
    Use -v to see a list of the files searched for.
   |
13 | import Text.Regex
   | ^^^^^^^^^^^^^^^^^
make[1]: *** [nofib-analyse] Error 1
Failed making boot in nofib-analyse: 1
make: *** [boot] Error 1

This adds the same information that is provided in the nofib wiki.

README.md

@@ -24,6 +24,7 @@ system GHC:
 Then, to run the tests, execute:
 
 ```
+$ cabal install html regex-compat
 $ make clean # or git clean -fxd, it's faster
 $ # Generates input files for the benchmarks and builds compilation
 $ # dependencies for make (ghc -M)