update docs

Author: nomadbl

docs/src/custom_behaviour.md

@@ -5,7 +5,7 @@ value is sent to:
 
   - `::AbstractVector{<:Real}` -> [Histogram backend](https://www.tensorflow.org/guide/tensorboard_histograms) as a vector
   - `::StatsBase.Histogram` -> [Histogram backend](https://www.tensorflow.org/guide/tensorboard_histograms)
-  - `(bin_edges, weights)::Tuple{AbstractVector,AbstractVector}` where `length(bin_edges)==length(weights)+1`, is interpreted as an histogram. (*Will be deprecated.* Please use `TBHistogram(edges, weights)` for this).
+  <!-- - `(bin_edges, weights)::Tuple{AbstractVector,AbstractVector}` where `length(bin_edges)==length(weights)+1`, is interpreted as an histogram. (*Will be deprecated.* Please use `TBHistogram(edges, weights)` for this). -->
   - `::Real` -> Scalar backend
   - `::AbstractArray{<:Colorant}` -> [Image backend](https://www.tensorflow.org/tensorboard/r2/image_summaries)
   - `::Any` -> Text Backend

docs/src/extending_behaviour.md

@@ -12,7 +12,7 @@ At the end of this step, every pair in `objects` will be logged to a specific
 backend, according to the following rules:
 
   - `::AbstractVector{<:Real}` -> [Histogram backend](https://www.tensorflow.org/guide/tensorboard_histograms) as a vector
-  - `::Tuple{AbstractVector,AbstractVector}` [Histogram backend](https://www.tensorflow.org/guide/tensorboard_histograms) as an histogram
+  <!-- - `::Tuple{AbstractVector,AbstractVector}` [Histogram backend](https://www.tensorflow.org/guide/tensorboard_histograms) as an histogram -->
   - `::Real` -> Scalar backend
   - `::AbstractArray{<:Colorant}` -> [Image backend](https://www.tensorflow.org/tensorboard/r2/image_summaries)
   - `::Any` -> Text Backend

docs/src/index.md

@@ -111,6 +111,7 @@ at [Reading back TensorBoard data](@ref)
 We also support logging custom types from a the following third-party libraries:
  - [Plots.jl](https://github.com/JuliaPlots/Plots.jl): the `Plots.Plot` type will be rendered to PNG at the resolution specified by the object and logged as an image
  - [PyPlot.jl](https://github.com/JuliaPy/PyPlot.jl): the `PyPlot.Figure` type will be rendered to PNG at the resolution specified by the object and logged as an image
+ - [Gadfly.jl](https://github.com/GiovineItalia/Gadfly.jl): the `Gadfly.Plot` type will be rendered to PNG at the resolution specified by the object and logged as an image
  - [Tracker.jl](https://github.com/FluxML/Tracker.jl): the `TrackedReal` and `TrackedArray` types will be logged as vector data
  - [ValueHistories.jl](https://github.com/JuliaML/ValueHistories.jl): the `MVHistory` type is used to store the deserialized content of .proto files.