Add copyright / permission on documentation and documentation version up

Permission obtained via e-mail exchange:

I (Robert Wolff) wrote:
> [...] For testing purposes the Neuroscience community collects small samples of
> raw traces [...]. Some little test files have been uploaded
> already in the older (brw 3.x) and newer (brw 4.x) file formats.
> I’d like to ask your permission to upload the concerning documentation
g PDFs. I have here two versions:
> 1) Documentation of brw 3.x and bxr 2.x, document version 1.2.0 [...]
> 2) Documentation of brw 4.x, bxr 3.x and bcmp 1.x, document version
> 1.0.0 [...]

and received following answer from Alessandro Maccione:
> no problem to share the documentation, please go ahead,
> anyhow for the brw 4.x, bxr 3.x and bcmp 1.x, document, I attached the most
> recent version (1.1.3)

biocam/README.md

@@ -1,4 +1,4 @@
-# Test files from [3Brain](https://www.3brain.com/) electrophysiology recording systems
+# Test files from [3Brain](https://www.3brain.com) electrophysiology recording systems
 ## BrainWave 4 and 5-generated test files provided by:
 
 * Alessia Polito
@@ -24,4 +24,6 @@ LuMIn, École Normale Supérieure Paris-Saclay, Gif-sur-Yvette, France
 
 ## Documentation of file formats
 * BrainWave 3-4: [documentation_brw_3.x_bxr_2.x_in_brainwave_3.x_and_4.x_v1.2.0.pdf](documentation_brw_3.x_bxr_2.x_in_brainwave_3.x_and_4.x_v1.2.0.pdf)
-* BrainWave 5: [documentation_brw_4.x_bxr_3.x_bcmp_1.x_in_brainwave_5.x_v1.0.0.pdf](documentation_brw_4.x_bxr_3.x_bcmp_1.x_in_brainwave_5.x_v1.0.0.pdf)
+* BrainWave 5: [documentation_brw_4.x_bxr_3.x_bcmp_1.x_in_brainwave_5.x_v1.1.3.pdf](documentation_brw_4.x_bxr_3.x_bcmp_1.x_in_brainwave_5.x_v1.1.3.pdf)
+
+The sharing of documentation files (copyright by 3Brain) on this repository was kindly permitted by Alessandro Maccione from [3Brain](https://www.3brain.com).